diff --git a/Tethering/common/TetheringLib/api/current.txt b/Tethering/common/TetheringLib/api/current.txt
new file mode 100644
index 0000000..d802177
--- /dev/null
+++ b/Tethering/common/TetheringLib/api/current.txt
@@ -0,0 +1 @@
+// Signature format: 2.0
diff --git a/Tethering/common/TetheringLib/api/module-lib-current.txt b/Tethering/common/TetheringLib/api/module-lib-current.txt
new file mode 100644
index 0000000..754584e
--- /dev/null
+++ b/Tethering/common/TetheringLib/api/module-lib-current.txt
@@ -0,0 +1,129 @@
+// Signature format: 2.0
+package android.net {
+
+  public final class TetheredClient implements android.os.Parcelable {
+    ctor public TetheredClient(@NonNull android.net.MacAddress, @NonNull java.util.Collection<android.net.TetheredClient.AddressInfo>, int);
+    method public int describeContents();
+    method @NonNull public java.util.List<android.net.TetheredClient.AddressInfo> getAddresses();
+    method @NonNull public android.net.MacAddress getMacAddress();
+    method public int getTetheringType();
+    method public void writeToParcel(@NonNull android.os.Parcel, int);
+    field @NonNull public static final android.os.Parcelable.Creator<android.net.TetheredClient> CREATOR;
+  }
+
+  public static final class TetheredClient.AddressInfo implements android.os.Parcelable {
+    method public int describeContents();
+    method @NonNull public android.net.LinkAddress getAddress();
+    method @Nullable public String getHostname();
+    method public void writeToParcel(@NonNull android.os.Parcel, int);
+    field @NonNull public static final android.os.Parcelable.Creator<android.net.TetheredClient.AddressInfo> CREATOR;
+  }
+
+  public final class TetheringConstants {
+    field public static final String EXTRA_ADD_TETHER_TYPE = "extraAddTetherType";
+    field public static final String EXTRA_PROVISION_CALLBACK = "extraProvisionCallback";
+    field public static final String EXTRA_REM_TETHER_TYPE = "extraRemTetherType";
+    field public static final String EXTRA_RUN_PROVISION = "extraRunProvision";
+    field public static final String EXTRA_SET_ALARM = "extraSetAlarm";
+  }
+
+  public class TetheringManager {
+    ctor public TetheringManager(@NonNull android.content.Context, @NonNull java.util.function.Supplier<android.os.IBinder>);
+    method public int getLastTetherError(@NonNull String);
+    method @NonNull public String[] getTetherableBluetoothRegexs();
+    method @NonNull public String[] getTetherableIfaces();
+    method @NonNull public String[] getTetherableUsbRegexs();
+    method @NonNull public String[] getTetherableWifiRegexs();
+    method @NonNull public String[] getTetheredIfaces();
+    method @NonNull public String[] getTetheringErroredIfaces();
+    method public boolean isTetheringSupported();
+    method public boolean isTetheringSupported(@NonNull String);
+    method @RequiresPermission(android.Manifest.permission.ACCESS_NETWORK_STATE) public void registerTetheringEventCallback(@NonNull java.util.concurrent.Executor, @NonNull android.net.TetheringManager.TetheringEventCallback);
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.WRITE_SETTINGS}) public void requestLatestTetheringEntitlementResult(int, boolean, @NonNull java.util.concurrent.Executor, @NonNull android.net.TetheringManager.OnTetheringEntitlementResultListener);
+    method public void requestLatestTetheringEntitlementResult(int, @NonNull android.os.ResultReceiver, boolean);
+    method @Deprecated public int setUsbTethering(boolean);
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.WRITE_SETTINGS}) public void startTethering(@NonNull android.net.TetheringManager.TetheringRequest, @NonNull java.util.concurrent.Executor, @NonNull android.net.TetheringManager.StartTetheringCallback);
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.WRITE_SETTINGS}) public void startTethering(int, @NonNull java.util.concurrent.Executor, @NonNull android.net.TetheringManager.StartTetheringCallback);
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.WRITE_SETTINGS}) public void stopAllTethering();
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.WRITE_SETTINGS}) public void stopTethering(int);
+    method @Deprecated public int tether(@NonNull String);
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.ACCESS_NETWORK_STATE}) public void unregisterTetheringEventCallback(@NonNull android.net.TetheringManager.TetheringEventCallback);
+    method @Deprecated public int untether(@NonNull String);
+    field public static final String ACTION_TETHER_STATE_CHANGED = "android.net.conn.TETHER_STATE_CHANGED";
+    field public static final String EXTRA_ACTIVE_LOCAL_ONLY = "android.net.extra.ACTIVE_LOCAL_ONLY";
+    field public static final String EXTRA_ACTIVE_TETHER = "tetherArray";
+    field public static final String EXTRA_AVAILABLE_TETHER = "availableArray";
+    field public static final String EXTRA_ERRORED_TETHER = "erroredArray";
+    field public static final int TETHERING_BLUETOOTH = 2; // 0x2
+    field public static final int TETHERING_ETHERNET = 5; // 0x5
+    field public static final int TETHERING_INVALID = -1; // 0xffffffff
+    field public static final int TETHERING_NCM = 4; // 0x4
+    field public static final int TETHERING_USB = 1; // 0x1
+    field public static final int TETHERING_WIFI = 0; // 0x0
+    field public static final int TETHERING_WIFI_P2P = 3; // 0x3
+    field public static final int TETHER_ERROR_DHCPSERVER_ERROR = 12; // 0xc
+    field public static final int TETHER_ERROR_DISABLE_FORWARDING_ERROR = 9; // 0x9
+    field public static final int TETHER_ERROR_ENABLE_FORWARDING_ERROR = 8; // 0x8
+    field public static final int TETHER_ERROR_ENTITLEMENT_UNKNOWN = 13; // 0xd
+    field public static final int TETHER_ERROR_IFACE_CFG_ERROR = 10; // 0xa
+    field public static final int TETHER_ERROR_INTERNAL_ERROR = 5; // 0x5
+    field public static final int TETHER_ERROR_NO_ACCESS_TETHERING_PERMISSION = 15; // 0xf
+    field public static final int TETHER_ERROR_NO_CHANGE_TETHERING_PERMISSION = 14; // 0xe
+    field public static final int TETHER_ERROR_NO_ERROR = 0; // 0x0
+    field public static final int TETHER_ERROR_PROVISIONING_FAILED = 11; // 0xb
+    field public static final int TETHER_ERROR_SERVICE_UNAVAIL = 2; // 0x2
+    field public static final int TETHER_ERROR_TETHER_IFACE_ERROR = 6; // 0x6
+    field public static final int TETHER_ERROR_UNAVAIL_IFACE = 4; // 0x4
+    field public static final int TETHER_ERROR_UNKNOWN_IFACE = 1; // 0x1
+    field public static final int TETHER_ERROR_UNKNOWN_TYPE = 16; // 0x10
+    field public static final int TETHER_ERROR_UNSUPPORTED = 3; // 0x3
+    field public static final int TETHER_ERROR_UNTETHER_IFACE_ERROR = 7; // 0x7
+    field public static final int TETHER_HARDWARE_OFFLOAD_FAILED = 2; // 0x2
+    field public static final int TETHER_HARDWARE_OFFLOAD_STARTED = 1; // 0x1
+    field public static final int TETHER_HARDWARE_OFFLOAD_STOPPED = 0; // 0x0
+  }
+
+  public static interface TetheringManager.OnTetheringEntitlementResultListener {
+    method public void onTetheringEntitlementResult(int);
+  }
+
+  public static interface TetheringManager.StartTetheringCallback {
+    method public default void onTetheringFailed(int);
+    method public default void onTetheringStarted();
+  }
+
+  public static interface TetheringManager.TetheringEventCallback {
+    method public default void onClientsChanged(@NonNull java.util.Collection<android.net.TetheredClient>);
+    method public default void onError(@NonNull String, int);
+    method public default void onOffloadStatusChanged(int);
+    method public default void onTetherableInterfaceRegexpsChanged(@NonNull android.net.TetheringManager.TetheringInterfaceRegexps);
+    method public default void onTetherableInterfacesChanged(@NonNull java.util.List<java.lang.String>);
+    method public default void onTetheredInterfacesChanged(@NonNull java.util.List<java.lang.String>);
+    method public default void onTetheringSupported(boolean);
+    method public default void onUpstreamChanged(@Nullable android.net.Network);
+  }
+
+  public static class TetheringManager.TetheringInterfaceRegexps {
+    method @NonNull public java.util.List<java.lang.String> getTetherableBluetoothRegexs();
+    method @NonNull public java.util.List<java.lang.String> getTetherableUsbRegexs();
+    method @NonNull public java.util.List<java.lang.String> getTetherableWifiRegexs();
+  }
+
+  public static class TetheringManager.TetheringRequest {
+    method @Nullable public android.net.LinkAddress getClientStaticIpv4Address();
+    method @Nullable public android.net.LinkAddress getLocalIpv4Address();
+    method public boolean getShouldShowEntitlementUi();
+    method public int getTetheringType();
+    method public boolean isExemptFromEntitlementCheck();
+  }
+
+  public static class TetheringManager.TetheringRequest.Builder {
+    ctor public TetheringManager.TetheringRequest.Builder(int);
+    method @NonNull public android.net.TetheringManager.TetheringRequest build();
+    method @NonNull @RequiresPermission(android.Manifest.permission.TETHER_PRIVILEGED) public android.net.TetheringManager.TetheringRequest.Builder setExemptFromEntitlementCheck(boolean);
+    method @NonNull @RequiresPermission(android.Manifest.permission.TETHER_PRIVILEGED) public android.net.TetheringManager.TetheringRequest.Builder setShouldShowEntitlementUi(boolean);
+    method @NonNull @RequiresPermission(android.Manifest.permission.TETHER_PRIVILEGED) public android.net.TetheringManager.TetheringRequest.Builder setStaticIpv4Addresses(@NonNull android.net.LinkAddress, @NonNull android.net.LinkAddress);
+  }
+
+}
+
diff --git a/Tethering/common/TetheringLib/api/module-lib-removed.txt b/Tethering/common/TetheringLib/api/module-lib-removed.txt
new file mode 100644
index 0000000..d802177
--- /dev/null
+++ b/Tethering/common/TetheringLib/api/module-lib-removed.txt
@@ -0,0 +1 @@
+// Signature format: 2.0
diff --git a/Tethering/common/TetheringLib/api/removed.txt b/Tethering/common/TetheringLib/api/removed.txt
new file mode 100644
index 0000000..d802177
--- /dev/null
+++ b/Tethering/common/TetheringLib/api/removed.txt
@@ -0,0 +1 @@
+// Signature format: 2.0
diff --git a/Tethering/common/TetheringLib/api/system-current.txt b/Tethering/common/TetheringLib/api/system-current.txt
new file mode 100644
index 0000000..edd1ebb
--- /dev/null
+++ b/Tethering/common/TetheringLib/api/system-current.txt
@@ -0,0 +1,99 @@
+// Signature format: 2.0
+package android.net {
+
+  public final class TetheredClient implements android.os.Parcelable {
+    ctor public TetheredClient(@NonNull android.net.MacAddress, @NonNull java.util.Collection<android.net.TetheredClient.AddressInfo>, int);
+    method public int describeContents();
+    method @NonNull public java.util.List<android.net.TetheredClient.AddressInfo> getAddresses();
+    method @NonNull public android.net.MacAddress getMacAddress();
+    method public int getTetheringType();
+    method public void writeToParcel(@NonNull android.os.Parcel, int);
+    field @NonNull public static final android.os.Parcelable.Creator<android.net.TetheredClient> CREATOR;
+  }
+
+  public static final class TetheredClient.AddressInfo implements android.os.Parcelable {
+    method public int describeContents();
+    method @NonNull public android.net.LinkAddress getAddress();
+    method @Nullable public String getHostname();
+    method public void writeToParcel(@NonNull android.os.Parcel, int);
+    field @NonNull public static final android.os.Parcelable.Creator<android.net.TetheredClient.AddressInfo> CREATOR;
+  }
+
+  public class TetheringManager {
+    method @RequiresPermission(android.Manifest.permission.ACCESS_NETWORK_STATE) public void registerTetheringEventCallback(@NonNull java.util.concurrent.Executor, @NonNull android.net.TetheringManager.TetheringEventCallback);
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.WRITE_SETTINGS}) public void requestLatestTetheringEntitlementResult(int, boolean, @NonNull java.util.concurrent.Executor, @NonNull android.net.TetheringManager.OnTetheringEntitlementResultListener);
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.WRITE_SETTINGS}) public void startTethering(@NonNull android.net.TetheringManager.TetheringRequest, @NonNull java.util.concurrent.Executor, @NonNull android.net.TetheringManager.StartTetheringCallback);
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.WRITE_SETTINGS}) public void stopAllTethering();
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.WRITE_SETTINGS}) public void stopTethering(int);
+    method @RequiresPermission(anyOf={android.Manifest.permission.TETHER_PRIVILEGED, android.Manifest.permission.ACCESS_NETWORK_STATE}) public void unregisterTetheringEventCallback(@NonNull android.net.TetheringManager.TetheringEventCallback);
+    field public static final String ACTION_TETHER_STATE_CHANGED = "android.net.conn.TETHER_STATE_CHANGED";
+    field public static final String EXTRA_ACTIVE_LOCAL_ONLY = "android.net.extra.ACTIVE_LOCAL_ONLY";
+    field public static final String EXTRA_ACTIVE_TETHER = "tetherArray";
+    field public static final String EXTRA_AVAILABLE_TETHER = "availableArray";
+    field public static final String EXTRA_ERRORED_TETHER = "erroredArray";
+    field public static final int TETHERING_BLUETOOTH = 2; // 0x2
+    field public static final int TETHERING_ETHERNET = 5; // 0x5
+    field public static final int TETHERING_INVALID = -1; // 0xffffffff
+    field public static final int TETHERING_NCM = 4; // 0x4
+    field public static final int TETHERING_USB = 1; // 0x1
+    field public static final int TETHERING_WIFI = 0; // 0x0
+    field public static final int TETHERING_WIFI_P2P = 3; // 0x3
+    field public static final int TETHER_ERROR_DHCPSERVER_ERROR = 12; // 0xc
+    field public static final int TETHER_ERROR_DISABLE_FORWARDING_ERROR = 9; // 0x9
+    field public static final int TETHER_ERROR_ENABLE_FORWARDING_ERROR = 8; // 0x8
+    field public static final int TETHER_ERROR_ENTITLEMENT_UNKNOWN = 13; // 0xd
+    field public static final int TETHER_ERROR_IFACE_CFG_ERROR = 10; // 0xa
+    field public static final int TETHER_ERROR_INTERNAL_ERROR = 5; // 0x5
+    field public static final int TETHER_ERROR_NO_ACCESS_TETHERING_PERMISSION = 15; // 0xf
+    field public static final int TETHER_ERROR_NO_CHANGE_TETHERING_PERMISSION = 14; // 0xe
+    field public static final int TETHER_ERROR_NO_ERROR = 0; // 0x0
+    field public static final int TETHER_ERROR_PROVISIONING_FAILED = 11; // 0xb
+    field public static final int TETHER_ERROR_SERVICE_UNAVAIL = 2; // 0x2
+    field public static final int TETHER_ERROR_TETHER_IFACE_ERROR = 6; // 0x6
+    field public static final int TETHER_ERROR_UNAVAIL_IFACE = 4; // 0x4
+    field public static final int TETHER_ERROR_UNKNOWN_IFACE = 1; // 0x1
+    field public static final int TETHER_ERROR_UNKNOWN_TYPE = 16; // 0x10
+    field public static final int TETHER_ERROR_UNSUPPORTED = 3; // 0x3
+    field public static final int TETHER_ERROR_UNTETHER_IFACE_ERROR = 7; // 0x7
+    field public static final int TETHER_HARDWARE_OFFLOAD_FAILED = 2; // 0x2
+    field public static final int TETHER_HARDWARE_OFFLOAD_STARTED = 1; // 0x1
+    field public static final int TETHER_HARDWARE_OFFLOAD_STOPPED = 0; // 0x0
+  }
+
+  public static interface TetheringManager.OnTetheringEntitlementResultListener {
+    method public void onTetheringEntitlementResult(int);
+  }
+
+  public static interface TetheringManager.StartTetheringCallback {
+    method public default void onTetheringFailed(int);
+    method public default void onTetheringStarted();
+  }
+
+  public static interface TetheringManager.TetheringEventCallback {
+    method public default void onClientsChanged(@NonNull java.util.Collection<android.net.TetheredClient>);
+    method public default void onError(@NonNull String, int);
+    method public default void onOffloadStatusChanged(int);
+    method public default void onTetherableInterfacesChanged(@NonNull java.util.List<java.lang.String>);
+    method public default void onTetheredInterfacesChanged(@NonNull java.util.List<java.lang.String>);
+    method public default void onTetheringSupported(boolean);
+    method public default void onUpstreamChanged(@Nullable android.net.Network);
+  }
+
+  public static class TetheringManager.TetheringRequest {
+    method @Nullable public android.net.LinkAddress getClientStaticIpv4Address();
+    method @Nullable public android.net.LinkAddress getLocalIpv4Address();
+    method public boolean getShouldShowEntitlementUi();
+    method public int getTetheringType();
+    method public boolean isExemptFromEntitlementCheck();
+  }
+
+  public static class TetheringManager.TetheringRequest.Builder {
+    ctor public TetheringManager.TetheringRequest.Builder(int);
+    method @NonNull public android.net.TetheringManager.TetheringRequest build();
+    method @NonNull @RequiresPermission(android.Manifest.permission.TETHER_PRIVILEGED) public android.net.TetheringManager.TetheringRequest.Builder setExemptFromEntitlementCheck(boolean);
+    method @NonNull @RequiresPermission(android.Manifest.permission.TETHER_PRIVILEGED) public android.net.TetheringManager.TetheringRequest.Builder setShouldShowEntitlementUi(boolean);
+    method @NonNull @RequiresPermission(android.Manifest.permission.TETHER_PRIVILEGED) public android.net.TetheringManager.TetheringRequest.Builder setStaticIpv4Addresses(@NonNull android.net.LinkAddress, @NonNull android.net.LinkAddress);
+  }
+
+}
+
diff --git a/Tethering/common/TetheringLib/api/system-removed.txt b/Tethering/common/TetheringLib/api/system-removed.txt
new file mode 100644
index 0000000..d802177
--- /dev/null
+++ b/Tethering/common/TetheringLib/api/system-removed.txt
@@ -0,0 +1 @@
+// Signature format: 2.0
diff --git a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
index f8f89e7..096f4fe 100644
--- a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
+++ b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
@@ -115,6 +115,19 @@
      */
     public static final String EXTRA_ERRORED_TETHER = "erroredArray";
 
+    /** @hide */
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef(flag = false, value = {
+            TETHERING_WIFI,
+            TETHERING_USB,
+            TETHERING_BLUETOOTH,
+            TETHERING_WIFI_P2P,
+            TETHERING_NCM,
+            TETHERING_ETHERNET,
+    })
+    public @interface TetheringType {
+    }
+
     /**
      * Invalid tethering type.
      * @see #startTethering.
@@ -158,22 +171,60 @@
      */
     public static final int TETHERING_ETHERNET = 5;
 
-    public static final int TETHER_ERROR_NO_ERROR           = 0;
-    public static final int TETHER_ERROR_UNKNOWN_IFACE      = 1;
-    public static final int TETHER_ERROR_SERVICE_UNAVAIL    = 2;
-    public static final int TETHER_ERROR_UNSUPPORTED        = 3;
-    public static final int TETHER_ERROR_UNAVAIL_IFACE      = 4;
-    public static final int TETHER_ERROR_MASTER_ERROR       = 5;
+    /** @hide */
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef(value = {
+            TETHER_ERROR_NO_ERROR,
+            TETHER_ERROR_PROVISIONING_FAILED,
+            TETHER_ERROR_ENTITLEMENT_UNKNOWN,
+    })
+    public @interface EntitlementResult {
+    }
+
+    /** @hide */
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef(value = {
+            TETHER_ERROR_NO_ERROR,
+            TETHER_ERROR_UNKNOWN_IFACE,
+            TETHER_ERROR_SERVICE_UNAVAIL,
+            TETHER_ERROR_INTERNAL_ERROR,
+            TETHER_ERROR_TETHER_IFACE_ERROR,
+            TETHER_ERROR_ENABLE_FORWARDING_ERROR,
+            TETHER_ERROR_DISABLE_FORWARDING_ERROR,
+            TETHER_ERROR_IFACE_CFG_ERROR,
+            TETHER_ERROR_DHCPSERVER_ERROR,
+    })
+    public @interface TetheringIfaceError {
+    }
+
+    /** @hide */
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef(value = {
+            TETHER_ERROR_SERVICE_UNAVAIL,
+            TETHER_ERROR_INTERNAL_ERROR,
+            TETHER_ERROR_NO_CHANGE_TETHERING_PERMISSION,
+            TETHER_ERROR_UNKNOWN_TYPE,
+    })
+    public @interface StartTetheringError {
+    }
+
+    public static final int TETHER_ERROR_NO_ERROR = 0;
+    public static final int TETHER_ERROR_UNKNOWN_IFACE = 1;
+    public static final int TETHER_ERROR_SERVICE_UNAVAIL = 2;
+    public static final int TETHER_ERROR_UNSUPPORTED = 3;
+    public static final int TETHER_ERROR_UNAVAIL_IFACE = 4;
+    public static final int TETHER_ERROR_INTERNAL_ERROR = 5;
     public static final int TETHER_ERROR_TETHER_IFACE_ERROR = 6;
     public static final int TETHER_ERROR_UNTETHER_IFACE_ERROR = 7;
-    public static final int TETHER_ERROR_ENABLE_NAT_ERROR     = 8;
-    public static final int TETHER_ERROR_DISABLE_NAT_ERROR    = 9;
-    public static final int TETHER_ERROR_IFACE_CFG_ERROR      = 10;
-    public static final int TETHER_ERROR_PROVISION_FAILED     = 11;
-    public static final int TETHER_ERROR_DHCPSERVER_ERROR     = 12;
+    public static final int TETHER_ERROR_ENABLE_FORWARDING_ERROR = 8;
+    public static final int TETHER_ERROR_DISABLE_FORWARDING_ERROR = 9;
+    public static final int TETHER_ERROR_IFACE_CFG_ERROR = 10;
+    public static final int TETHER_ERROR_PROVISIONING_FAILED = 11;
+    public static final int TETHER_ERROR_DHCPSERVER_ERROR = 12;
     public static final int TETHER_ERROR_ENTITLEMENT_UNKNOWN = 13;
     public static final int TETHER_ERROR_NO_CHANGE_TETHERING_PERMISSION = 14;
     public static final int TETHER_ERROR_NO_ACCESS_TETHERING_PERMISSION = 15;
+    public static final int TETHER_ERROR_UNKNOWN_TYPE = 16;
 
     /** @hide */
     @Retention(RetentionPolicy.SOURCE)
@@ -508,7 +559,7 @@
             private final TetheringRequestParcel mBuilderParcel;
 
             /** Default constructor of Builder. */
-            public Builder(final int type) {
+            public Builder(@TetheringType final int type) {
                 mBuilderParcel = new TetheringRequestParcel();
                 mBuilderParcel.tetheringType = type;
                 mBuilderParcel.localIPv4Address = null;
@@ -553,11 +604,14 @@
                 return this;
             }
 
-            /** Start tethering without showing the provisioning UI. */
+            /**
+             * If an entitlement check is needed, sets whether to show the entitlement UI or to
+             * perform a silent entitlement check. By default, the entitlement UI is shown.
+             */
             @RequiresPermission(android.Manifest.permission.TETHER_PRIVILEGED)
             @NonNull
-            public Builder setSilentProvisioning(boolean silent) {
-                mBuilderParcel.showProvisioningUi = silent;
+            public Builder setShouldShowEntitlementUi(boolean showUi) {
+                mBuilderParcel.showProvisioningUi = showUi;
                 return this;
             }
 
@@ -566,18 +620,40 @@
             public TetheringRequest build() {
                 return new TetheringRequest(mBuilderParcel);
             }
+        }
 
-            /** Get static server address. */
-            @Nullable
-            public LinkAddress getLocalIpv4Address() {
-                return mBuilderParcel.localIPv4Address;
-            }
+        /**
+         * Get the local IPv4 address, if one was configured with
+         * {@link Builder#setStaticIpv4Addresses}.
+         */
+        @Nullable
+        public LinkAddress getLocalIpv4Address() {
+            return mRequestParcel.localIPv4Address;
+        }
 
-            /** Get static client address. */
-            @Nullable
-            public LinkAddress getClientStaticIpv4Address() {
-                return mBuilderParcel.staticClientAddress;
-            }
+        /**
+         * Get the static IPv4 address of the client, if one was configured with
+         * {@link Builder#setStaticIpv4Addresses}.
+         */
+        @Nullable
+        public LinkAddress getClientStaticIpv4Address() {
+            return mRequestParcel.staticClientAddress;
+        }
+
+        /** Get tethering type. */
+        @TetheringType
+        public int getTetheringType() {
+            return mRequestParcel.tetheringType;
+        }
+
+        /** Check if exempt from entitlement check. */
+        public boolean isExemptFromEntitlementCheck() {
+            return mRequestParcel.exemptFromEntitlementCheck;
+        }
+
+        /** Check if show entitlement ui.  */
+        public boolean getShouldShowEntitlementUi() {
+            return mRequestParcel.showProvisioningUi;
         }
 
         /**
@@ -602,18 +678,18 @@
     /**
      * Callback for use with {@link #startTethering} to find out whether tethering succeeded.
      */
-    public abstract static class StartTetheringCallback {
+    public interface StartTetheringCallback {
         /**
          * Called when tethering has been successfully started.
          */
-        public void onTetheringStarted() {}
+        default void onTetheringStarted() {}
 
         /**
          * Called when starting tethering failed.
          *
-         * @param resultCode One of the {@code TETHER_ERROR_*} constants.
+         * @param error The error that caused the failure.
          */
-        public void onTetheringFailed(final int resultCode) {}
+        default void onTetheringFailed(@StartTetheringError final int error) {}
     }
 
     /**
@@ -663,11 +739,13 @@
      * @param type The tethering type, on of the {@code TetheringManager#TETHERING_*} constants.
      * @param executor {@link Executor} to specify the thread upon which the callback of
      *         TetheringRequest will be invoked.
+     * @hide
      */
     @RequiresPermission(anyOf = {
             android.Manifest.permission.TETHER_PRIVILEGED,
             android.Manifest.permission.WRITE_SETTINGS
     })
+    @SystemApi(client = MODULE_LIBRARIES)
     public void startTethering(int type, @NonNull final Executor executor,
             @NonNull final StartTetheringCallback callback) {
         startTethering(new TetheringRequest.Builder(type).build(), executor, callback);
@@ -684,7 +762,7 @@
             android.Manifest.permission.TETHER_PRIVILEGED,
             android.Manifest.permission.WRITE_SETTINGS
     })
-    public void stopTethering(final int type) {
+    public void stopTethering(@TetheringType final int type) {
         final String callerPkg = mContext.getOpPackageName();
         Log.i(TAG, "stopTethering caller:" + callerPkg);
 
@@ -709,10 +787,10 @@
          *
          * @param resultCode an int value of entitlement result. It may be one of
          *         {@link #TETHER_ERROR_NO_ERROR},
-         *         {@link #TETHER_ERROR_PROVISION_FAILED}, or
+         *         {@link #TETHER_ERROR_PROVISIONING_FAILED}, or
          *         {@link #TETHER_ERROR_ENTITLEMENT_UNKNOWN}.
          */
-        void onTetheringEntitlementResult(int resultCode);
+        void onTetheringEntitlementResult(@EntitlementResult int result);
     }
 
     /**
@@ -727,7 +805,8 @@
      * fail if a tethering entitlement check is required.
      *
      * @param type the downstream type of tethering. Must be one of {@code #TETHERING_*} constants.
-     * @param showEntitlementUi a boolean indicating whether to run UI-based entitlement check.
+     * @param showEntitlementUi a boolean indicating whether to check result for the UI-based
+     *         entitlement check or the silent entitlement check.
      * @param executor the executor on which callback will be invoked.
      * @param listener an {@link OnTetheringEntitlementResultListener} which will be called to
      *         notify the caller of the result of entitlement check. The listener may be called zero
@@ -737,7 +816,8 @@
             android.Manifest.permission.TETHER_PRIVILEGED,
             android.Manifest.permission.WRITE_SETTINGS
     })
-    public void requestLatestTetheringEntitlementResult(int type, boolean showEntitlementUi,
+    public void requestLatestTetheringEntitlementResult(@TetheringType int type,
+            boolean showEntitlementUi,
             @NonNull Executor executor,
             @NonNull final OnTetheringEntitlementResultListener listener) {
         if (listener == null) {
@@ -766,7 +846,7 @@
      */
     // TODO: improve the usage of ResultReceiver, b/145096122
     @SystemApi(client = MODULE_LIBRARIES)
-    public void requestLatestTetheringEntitlementResult(final int type,
+    public void requestLatestTetheringEntitlementResult(@TetheringType final int type,
             @NonNull final ResultReceiver receiver, final boolean showEntitlementUi) {
         final String callerPkg = mContext.getOpPackageName();
         Log.i(TAG, "getLatestTetheringEntitlementResult caller:" + callerPkg);
@@ -779,7 +859,7 @@
      * Callback for use with {@link registerTetheringEventCallback} to find out tethering
      * upstream status.
      */
-    public abstract static class TetheringEventCallback {
+    public interface TetheringEventCallback {
         /**
          * Called when tethering supported status changed.
          *
@@ -791,7 +871,7 @@
          *
          * @param supported The new supported status
          */
-        public void onTetheringSupported(boolean supported) {}
+        default void onTetheringSupported(boolean supported) {}
 
         /**
          * Called when tethering upstream changed.
@@ -802,7 +882,7 @@
          * @param network the {@link Network} of tethering upstream. Null means tethering doesn't
          * have any upstream.
          */
-        public void onUpstreamChanged(@Nullable Network network) {}
+        default void onUpstreamChanged(@Nullable Network network) {}
 
         /**
          * Called when there was a change in tethering interface regular expressions.
@@ -810,28 +890,30 @@
          * <p>This will be called immediately after the callback is registered, and may be called
          * multiple times later upon changes.
          * @param reg The new regular expressions.
-         * @deprecated Referencing interfaces by regular expressions is a deprecated mechanism.
+         *
+         * @hide
          */
-        @Deprecated
-        public void onTetherableInterfaceRegexpsChanged(@NonNull TetheringInterfaceRegexps reg) {}
+        @SystemApi(client = MODULE_LIBRARIES)
+        default void onTetherableInterfaceRegexpsChanged(@NonNull TetheringInterfaceRegexps reg) {}
 
         /**
-         * Called when there was a change in the list of tetherable interfaces.
+         * Called when there was a change in the list of tetherable interfaces. Tetherable
+         * interface means this interface is available and can be used for tethering.
          *
          * <p>This will be called immediately after the callback is registered, and may be called
          * multiple times later upon changes.
-         * @param interfaces The list of tetherable interfaces.
+         * @param interfaces The list of tetherable interface names.
          */
-        public void onTetherableInterfacesChanged(@NonNull List<String> interfaces) {}
+        default void onTetherableInterfacesChanged(@NonNull List<String> interfaces) {}
 
         /**
          * Called when there was a change in the list of tethered interfaces.
          *
          * <p>This will be called immediately after the callback is registered, and may be called
          * multiple times later upon changes.
-         * @param interfaces The list of tethered interfaces.
+         * @param interfaces The list of 0 or more String of currently tethered interface names.
          */
-        public void onTetheredInterfacesChanged(@NonNull List<String> interfaces) {}
+        default void onTetheredInterfacesChanged(@NonNull List<String> interfaces) {}
 
         /**
          * Called when an error occurred configuring tethering.
@@ -841,7 +923,7 @@
          * @param ifName Name of the interface.
          * @param error One of {@code TetheringManager#TETHER_ERROR_*}.
          */
-        public void onError(@NonNull String ifName, int error) {}
+        default void onError(@NonNull String ifName, @TetheringIfaceError int error) {}
 
         /**
          * Called when the list of tethered clients changes.
@@ -854,7 +936,7 @@
          * determine if they are still connected.
          * @param clients The new set of tethered clients; the collection is not ordered.
          */
-        public void onClientsChanged(@NonNull Collection<TetheredClient> clients) {}
+        default void onClientsChanged(@NonNull Collection<TetheredClient> clients) {}
 
         /**
          * Called when tethering offload status changes.
@@ -862,19 +944,20 @@
          * <p>This will be called immediately after the callback is registered.
          * @param status The offload status.
          */
-        public void onOffloadStatusChanged(@TetherOffloadStatus int status) {}
+        default void onOffloadStatusChanged(@TetherOffloadStatus int status) {}
     }
 
     /**
      * Regular expressions used to identify tethering interfaces.
-     * @deprecated Referencing interfaces by regular expressions is a deprecated mechanism.
+     * @hide
      */
-    @Deprecated
+    @SystemApi(client = MODULE_LIBRARIES)
     public static class TetheringInterfaceRegexps {
         private final String[] mTetherableBluetoothRegexs;
         private final String[] mTetherableUsbRegexs;
         private final String[] mTetherableWifiRegexs;
 
+        /** @hide */
         public TetheringInterfaceRegexps(@NonNull String[] tetherableBluetoothRegexs,
                 @NonNull String[] tetherableUsbRegexs, @NonNull String[] tetherableWifiRegexs) {
             mTetherableBluetoothRegexs = tetherableBluetoothRegexs.clone();
diff --git a/Tethering/res/values-mcc204-mnc04/strings.xml b/Tethering/res/values-mcc204-mnc04/strings.xml
new file mode 100644
index 0000000..a996b42
--- /dev/null
+++ b/Tethering/res/values-mcc204-mnc04/strings.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2020 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<resources>
+    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_title">Hotspot has no internet</string>
+    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_message">Devices can\u2019t connect to internet</string>
+    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
+    <string name="no_upstream_notification_disable_button">Turn off hotspot</string>
+
+    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
+    <string name="upstream_roaming_notification_title">Hotspot is on</string>
+    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
+    <string name="upstream_roaming_notification_message">Additional charges may apply while roaming</string>
+    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
+    <string name="upstream_roaming_notification_continue_button">Continue</string>
+</resources>
diff --git a/Tethering/res/values-mcc310-mnc004/strings.xml b/Tethering/res/values-mcc310-mnc004/strings.xml
new file mode 100644
index 0000000..a996b42
--- /dev/null
+++ b/Tethering/res/values-mcc310-mnc004/strings.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2020 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<resources>
+    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_title">Hotspot has no internet</string>
+    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_message">Devices can\u2019t connect to internet</string>
+    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
+    <string name="no_upstream_notification_disable_button">Turn off hotspot</string>
+
+    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
+    <string name="upstream_roaming_notification_title">Hotspot is on</string>
+    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
+    <string name="upstream_roaming_notification_message">Additional charges may apply while roaming</string>
+    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
+    <string name="upstream_roaming_notification_continue_button">Continue</string>
+</resources>
diff --git a/Tethering/res/values-mcc310-mnc120/strings.xml b/Tethering/res/values-mcc310-mnc120/strings.xml
new file mode 100644
index 0000000..618df90
--- /dev/null
+++ b/Tethering/res/values-mcc310-mnc120/strings.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2020 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
+    <!-- String for tethered notification title with client number info. -->
+    <plurals name="tethered_notification_title_with_client_number">
+        <item quantity="one"><xliff:g>%1$d</xliff:g> device connected.</item>
+        <item quantity="other"><xliff:g>%1$d</xliff:g> devices connected.</item>
+    </plurals>
+</resources>
\ No newline at end of file
diff --git a/Tethering/res/values-mcc311-mnc480/strings.xml b/Tethering/res/values-mcc311-mnc480/strings.xml
new file mode 100644
index 0000000..a996b42
--- /dev/null
+++ b/Tethering/res/values-mcc311-mnc480/strings.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2020 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<resources>
+    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_title">Hotspot has no internet</string>
+    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_message">Devices can\u2019t connect to internet</string>
+    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
+    <string name="no_upstream_notification_disable_button">Turn off hotspot</string>
+
+    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
+    <string name="upstream_roaming_notification_title">Hotspot is on</string>
+    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
+    <string name="upstream_roaming_notification_message">Additional charges may apply while roaming</string>
+    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
+    <string name="upstream_roaming_notification_continue_button">Continue</string>
+</resources>
diff --git a/Tethering/res/values-mcc311-mnc490/strings.xml b/Tethering/res/values-mcc311-mnc490/strings.xml
new file mode 100644
index 0000000..618df90
--- /dev/null
+++ b/Tethering/res/values-mcc311-mnc490/strings.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2020 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
+    <!-- String for tethered notification title with client number info. -->
+    <plurals name="tethered_notification_title_with_client_number">
+        <item quantity="one"><xliff:g>%1$d</xliff:g> device connected.</item>
+        <item quantity="other"><xliff:g>%1$d</xliff:g> devices connected.</item>
+    </plurals>
+</resources>
\ No newline at end of file
diff --git a/Tethering/res/values-mcc312-mnc530/strings.xml b/Tethering/res/values-mcc312-mnc530/strings.xml
new file mode 100644
index 0000000..618df90
--- /dev/null
+++ b/Tethering/res/values-mcc312-mnc530/strings.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2020 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
+    <!-- String for tethered notification title with client number info. -->
+    <plurals name="tethered_notification_title_with_client_number">
+        <item quantity="one"><xliff:g>%1$d</xliff:g> device connected.</item>
+        <item quantity="other"><xliff:g>%1$d</xliff:g> devices connected.</item>
+    </plurals>
+</resources>
\ No newline at end of file
diff --git a/Tethering/res/values/strings.xml b/Tethering/res/values/strings.xml
index ba98a66..52a1654 100644
--- a/Tethering/res/values/strings.xml
+++ b/Tethering/res/values/strings.xml
@@ -13,12 +13,15 @@
      See the License for the specific language governing permissions and
      limitations under the License.
 -->
-<resources>
+<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
     <!-- Shown when the device is tethered -->
     <!-- String for tethered notification title [CHAR LIMIT=200] -->
     <string name="tethered_notification_title">Tethering or hotspot active</string>
     <!-- String for tethered notification message [CHAR LIMIT=200] -->
     <string name="tethered_notification_message">Tap to set up.</string>
+    <!-- String for tethered notification title with client number info. -->
+    <plurals name="tethered_notification_title_with_client_number">
+    </plurals>
 
     <!-- This notification is shown when tethering has been disabled on a user's device.
     The device is managed by the user's employer. Tethering can't be turned on unless the
@@ -32,4 +35,18 @@
     Internet" settings page. That is currently the tether_settings_title_all string. -->
     <!-- String for tether notification channel name [CHAR LIMIT=200] -->
     <string name="notification_channel_tethering_status">Hotspot &amp; tethering status</string>
-</resources>
\ No newline at end of file
+
+    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_title"></string>
+    <!-- String for no upstream notification message [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_message"></string>
+    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
+    <string name="no_upstream_notification_disable_button"></string>
+
+    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
+    <string name="upstream_roaming_notification_title"></string>
+    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
+    <string name="upstream_roaming_notification_message"></string>
+    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
+    <string name="upstream_roaming_notification_continue_button"></string>
+</resources>
diff --git a/Tethering/src/android/net/ip/IpServer.java b/Tethering/src/android/net/ip/IpServer.java
index 433b903..c5478d2 100644
--- a/Tethering/src/android/net/ip/IpServer.java
+++ b/Tethering/src/android/net/ip/IpServer.java
@@ -1054,7 +1054,7 @@
                 case CMD_START_TETHERING_ERROR:
                 case CMD_STOP_TETHERING_ERROR:
                 case CMD_SET_DNS_FORWARDERS_ERROR:
-                    mLastError = TetheringManager.TETHER_ERROR_MASTER_ERROR;
+                    mLastError = TetheringManager.TETHER_ERROR_INTERNAL_ERROR;
                     transitionTo(mInitialState);
                     break;
                 default:
@@ -1185,7 +1185,7 @@
                         } catch (RemoteException | ServiceSpecificException e) {
                             mLog.e("Exception enabling NAT: " + e.toString());
                             cleanupUpstream();
-                            mLastError = TetheringManager.TETHER_ERROR_ENABLE_NAT_ERROR;
+                            mLastError = TetheringManager.TETHER_ERROR_ENABLE_FORWARDING_ERROR;
                             transitionTo(mInitialState);
                             return true;
                         }
diff --git a/Tethering/src/com/android/server/connectivity/tethering/EntitlementManager.java b/Tethering/src/com/android/server/connectivity/tethering/EntitlementManager.java
index e81d6ac..bd60594 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/EntitlementManager.java
+++ b/Tethering/src/com/android/server/connectivity/tethering/EntitlementManager.java
@@ -25,7 +25,7 @@
 import static android.net.TetheringManager.TETHERING_WIFI;
 import static android.net.TetheringManager.TETHER_ERROR_ENTITLEMENT_UNKNOWN;
 import static android.net.TetheringManager.TETHER_ERROR_NO_ERROR;
-import static android.net.TetheringManager.TETHER_ERROR_PROVISION_FAILED;
+import static android.net.TetheringManager.TETHER_ERROR_PROVISIONING_FAILED;
 
 import android.app.AlarmManager;
 import android.app.PendingIntent;
@@ -579,7 +579,7 @@
         switch (value) {
             case TETHER_ERROR_ENTITLEMENT_UNKNOWN: return "TETHER_ERROR_ENTITLEMENT_UNKONWN";
             case TETHER_ERROR_NO_ERROR: return "TETHER_ERROR_NO_ERROR";
-            case TETHER_ERROR_PROVISION_FAILED: return "TETHER_ERROR_PROVISION_FAILED";
+            case TETHER_ERROR_PROVISIONING_FAILED: return "TETHER_ERROR_PROVISIONING_FAILED";
             default:
                 return String.format("UNKNOWN ERROR (%d)", value);
         }
@@ -592,7 +592,7 @@
             protected void onReceiveResult(int resultCode, Bundle resultData) {
                 int updatedCacheValue = updateEntitlementCacheValue(type, resultCode);
                 addDownstreamMapping(type, updatedCacheValue);
-                if (updatedCacheValue == TETHER_ERROR_PROVISION_FAILED && notifyFail) {
+                if (updatedCacheValue == TETHER_ERROR_PROVISIONING_FAILED && notifyFail) {
                     mListener.onUiEntitlementFailed(type);
                 }
                 if (receiver != null) receiver.send(updatedCacheValue, null);
@@ -635,8 +635,8 @@
             mEntitlementCacheValue.put(type, resultCode);
             return resultCode;
         } else {
-            mEntitlementCacheValue.put(type, TETHER_ERROR_PROVISION_FAILED);
-            return TETHER_ERROR_PROVISION_FAILED;
+            mEntitlementCacheValue.put(type, TETHER_ERROR_PROVISIONING_FAILED);
+            return TETHER_ERROR_PROVISIONING_FAILED;
         }
     }
 
diff --git a/Tethering/src/com/android/server/connectivity/tethering/Tethering.java b/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
index 0be162c..020db54 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
+++ b/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
@@ -39,11 +39,12 @@
 import static android.net.TetheringManager.TETHERING_USB;
 import static android.net.TetheringManager.TETHERING_WIFI;
 import static android.net.TetheringManager.TETHERING_WIFI_P2P;
-import static android.net.TetheringManager.TETHER_ERROR_MASTER_ERROR;
+import static android.net.TetheringManager.TETHER_ERROR_INTERNAL_ERROR;
 import static android.net.TetheringManager.TETHER_ERROR_NO_ERROR;
 import static android.net.TetheringManager.TETHER_ERROR_SERVICE_UNAVAIL;
 import static android.net.TetheringManager.TETHER_ERROR_UNAVAIL_IFACE;
 import static android.net.TetheringManager.TETHER_ERROR_UNKNOWN_IFACE;
+import static android.net.TetheringManager.TETHER_ERROR_UNKNOWN_TYPE;
 import static android.net.TetheringManager.TETHER_HARDWARE_OFFLOAD_FAILED;
 import static android.net.TetheringManager.TETHER_HARDWARE_OFFLOAD_STARTED;
 import static android.net.TetheringManager.TETHER_HARDWARE_OFFLOAD_STOPPED;
@@ -302,7 +303,8 @@
 
         final UserManager userManager = (UserManager) mContext.getSystemService(
                 Context.USER_SERVICE);
-        mTetheringRestriction = new UserRestrictionActionListener(userManager, this);
+        mTetheringRestriction = new UserRestrictionActionListener(
+                userManager, this, mNotificationUpdater);
         mExecutor = new TetheringThreadExecutor(mHandler);
         mActiveDataSubIdListener = new ActiveDataSubIdListener(mExecutor);
 
@@ -368,9 +370,10 @@
 
             mActiveDataSubId = subId;
             updateConfiguration();
+            mNotificationUpdater.onActiveDataSubscriptionIdChanged(subId);
             // To avoid launching unexpected provisioning checks, ignore re-provisioning
             // when no CarrierConfig loaded yet. Assume reevaluateSimCardProvisioning()
-            // ill be triggered again when CarrierConfig is loaded.
+            // will be triggered again when CarrierConfig is loaded.
             if (mEntitlementMgr.getCarrierConfig(mConfig) != null) {
                 mEntitlementMgr.reevaluateSimCardProvisioning(mConfig);
             } else {
@@ -543,7 +546,7 @@
                 break;
             default:
                 Log.w(TAG, "Invalid tether type.");
-                result = TETHER_ERROR_UNKNOWN_IFACE;
+                result = TETHER_ERROR_UNKNOWN_TYPE;
         }
 
         // The result of Bluetooth tethering will be sent by #setBluetoothTethering.
@@ -584,7 +587,7 @@
             Binder.restoreCallingIdentity(ident);
         }
 
-        return TETHER_ERROR_MASTER_ERROR;
+        return TETHER_ERROR_INTERNAL_ERROR;
     }
 
     private void setBluetoothTethering(final boolean enable, final IIntResultListener listener) {
@@ -620,7 +623,7 @@
                 // We should figure out a way to bubble up that failure instead of sending success.
                 final int result = (((BluetoothPan) proxy).isTetheringOn() == enable)
                         ? TETHER_ERROR_NO_ERROR
-                        : TETHER_ERROR_MASTER_ERROR;
+                        : TETHER_ERROR_INTERNAL_ERROR;
                 sendTetherResult(listener, result, TETHERING_BLUETOOTH);
                 adapter.closeProfileProxy(BluetoothProfile.PAN, proxy);
             }
@@ -632,7 +635,10 @@
                 Context.ETHERNET_SERVICE);
         synchronized (mPublicSync) {
             if (enable) {
-                if (mEthernetCallback != null) return TETHER_ERROR_NO_ERROR;
+                if (mEthernetCallback != null) {
+                    Log.d(TAG, "Ethernet tethering already started");
+                    return TETHER_ERROR_NO_ERROR;
+                }
 
                 mEthernetCallback = new EthernetCallback();
                 mEthernetIfaceRequest = em.requestTetheredInterface(mExecutor, mEthernetCallback);
@@ -993,11 +999,14 @@
     protected static class UserRestrictionActionListener {
         private final UserManager mUserManager;
         private final Tethering mWrapper;
+        private final TetheringNotificationUpdater mNotificationUpdater;
         public boolean mDisallowTethering;
 
-        public UserRestrictionActionListener(UserManager um, Tethering wrapper) {
+        public UserRestrictionActionListener(@NonNull UserManager um, @NonNull Tethering wrapper,
+                @NonNull TetheringNotificationUpdater updater) {
             mUserManager = um;
             mWrapper = wrapper;
+            mNotificationUpdater = updater;
             mDisallowTethering = false;
         }
 
@@ -1016,13 +1025,21 @@
                 return;
             }
 
-            // TODO: Add user restrictions notification.
-            final boolean isTetheringActiveOnDevice = (mWrapper.getTetheredIfaces().length != 0);
-
-            if (newlyDisallowed && isTetheringActiveOnDevice) {
-                mWrapper.untetherAll();
-                // TODO(b/148139325): send tetheringSupported on restriction change
+            if (!newlyDisallowed) {
+                // Clear the restricted notification when user is allowed to have tethering
+                // function.
+                mNotificationUpdater.tetheringRestrictionLifted();
+                return;
             }
+
+            // Restricted notification is shown when tethering function is disallowed on
+            // user's device.
+            mNotificationUpdater.notifyTetheringDisabledByRestriction();
+
+            // Untether from all downstreams since tethering is disallowed.
+            mWrapper.untetherAll();
+
+            // TODO(b/148139325): send tetheringSupported on restriction change
         }
     }
 
@@ -1491,7 +1508,7 @@
             } else {
                 dnsServers = mConfig.defaultIPv4DNS;
             }
-            final int netId = (network != null) ? network.netId : NETID_UNSET;
+            final int netId = (network != null) ? network.getNetId() : NETID_UNSET;
             try {
                 mNetd.tetherDnsSet(netId, dnsServers);
                 mLog.log(String.format(
@@ -2182,7 +2199,7 @@
         // If TetherMasterSM is in ErrorState, TetherMasterSM stays there.
         // Thus we give a chance for TetherMasterSM to recover to InitialState
         // by sending CMD_CLEAR_ERROR
-        if (error == TETHER_ERROR_MASTER_ERROR) {
+        if (error == TETHER_ERROR_INTERNAL_ERROR) {
             mTetherMasterSM.sendMessage(TetherMasterSM.CMD_CLEAR_ERROR, who);
         }
         int which;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringNotificationUpdater.java b/Tethering/src/com/android/server/connectivity/tethering/TetheringNotificationUpdater.java
index b97f752..992cdd8 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringNotificationUpdater.java
+++ b/Tethering/src/com/android/server/connectivity/tethering/TetheringNotificationUpdater.java
@@ -29,12 +29,14 @@
 import android.content.res.Resources;
 import android.os.UserHandle;
 import android.provider.Settings;
+import android.telephony.SubscriptionManager;
 import android.text.TextUtils;
 import android.util.Log;
 import android.util.SparseArray;
 
 import androidx.annotation.ArrayRes;
 import androidx.annotation.DrawableRes;
+import androidx.annotation.IntDef;
 import androidx.annotation.IntRange;
 import androidx.annotation.NonNull;
 
@@ -54,10 +56,15 @@
 public class TetheringNotificationUpdater {
     private static final String TAG = TetheringNotificationUpdater.class.getSimpleName();
     private static final String CHANNEL_ID = "TETHERING_STATUS";
+    private static final String WIFI_DOWNSTREAM = "WIFI";
+    private static final String USB_DOWNSTREAM = "USB";
+    private static final String BLUETOOTH_DOWNSTREAM = "BT";
     private static final boolean NOTIFY_DONE = true;
     private static final boolean NO_NOTIFY = false;
     // Id to update and cancel tethering notification. Must be unique within the tethering app.
-    private static final int NOTIFY_ID = 20191115;
+    private static final int ENABLE_NOTIFICATION_ID = 1000;
+    // Id to update and cancel restricted notification. Must be unique within the tethering app.
+    private static final int RESTRICTED_NOTIFICATION_ID = 1001;
     @VisibleForTesting
     static final int NO_ICON_ID = 0;
     @VisibleForTesting
@@ -65,14 +72,25 @@
     private final Context mContext;
     private final NotificationManager mNotificationManager;
     private final NotificationChannel mChannel;
-    // Downstream type is one of ConnectivityManager.TETHERING_* constants, 0 1 or 2.
-    // This value has to be made 1 2 and 4, and OR'd with the others.
+
     // WARNING : the constructor is called on a different thread. Thread safety therefore
     // relies on this value being initialized to 0, and not any other value. If you need
     // to change this, you will need to change the thread where the constructor is invoked,
     // or to introduce synchronization.
+    // Downstream type is one of ConnectivityManager.TETHERING_* constants, 0 1 or 2.
+    // This value has to be made 1 2 and 4, and OR'd with the others.
     private int mDownstreamTypesMask = DOWNSTREAM_NONE;
 
+    // WARNING : this value is not able to being initialized to 0 and must have volatile because
+    // telephony service is not guaranteed that is up before tethering service starts. If telephony
+    // is up later than tethering, TetheringNotificationUpdater will use incorrect and valid
+    // subscription id(0) to query resources. Therefore, initialized subscription id must be
+    // INVALID_SUBSCRIPTION_ID.
+    private volatile int mActiveDataSubId = SubscriptionManager.INVALID_SUBSCRIPTION_ID;
+
+    @IntDef({ENABLE_NOTIFICATION_ID, RESTRICTED_NOTIFICATION_ID})
+    @interface NotificationId {}
+
     public TetheringNotificationUpdater(@NonNull final Context context) {
         mContext = context;
         mNotificationManager = (NotificationManager) context.createContextAsUser(UserHandle.ALL, 0)
@@ -88,19 +106,46 @@
     public void onDownstreamChanged(@IntRange(from = 0, to = 7) final int downstreamTypesMask) {
         if (mDownstreamTypesMask == downstreamTypesMask) return;
         mDownstreamTypesMask = downstreamTypesMask;
-        updateNotification();
+        updateEnableNotification();
     }
 
-    private void updateNotification() {
+    /** Called when active data subscription id changed */
+    public void onActiveDataSubscriptionIdChanged(final int subId) {
+        if (mActiveDataSubId == subId) return;
+        mActiveDataSubId = subId;
+        updateEnableNotification();
+    }
+
+    @VisibleForTesting
+    Resources getResourcesForSubId(@NonNull final Context c, final int subId) {
+        return SubscriptionManager.getResourcesForSubId(c, subId);
+    }
+
+    private void updateEnableNotification() {
         final boolean tetheringInactive = mDownstreamTypesMask <= DOWNSTREAM_NONE;
 
         if (tetheringInactive || setupNotification() == NO_NOTIFY) {
-            clearNotification();
+            clearNotification(ENABLE_NOTIFICATION_ID);
         }
     }
 
-    private void clearNotification() {
-        mNotificationManager.cancel(null /* tag */, NOTIFY_ID);
+    @VisibleForTesting
+    void tetheringRestrictionLifted() {
+        clearNotification(RESTRICTED_NOTIFICATION_ID);
+    }
+
+    private void clearNotification(@NotificationId final int id) {
+        mNotificationManager.cancel(null /* tag */, id);
+    }
+
+    @VisibleForTesting
+    void notifyTetheringDisabledByRestriction() {
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final String title = res.getString(R.string.disable_tether_notification_title);
+        final String message = res.getString(R.string.disable_tether_notification_message);
+
+        showNotification(R.drawable.stat_sys_tether_general, title, message,
+                RESTRICTED_NOTIFICATION_ID);
     }
 
     /**
@@ -110,16 +155,17 @@
      *
      * @return downstream types mask value.
      */
+    @VisibleForTesting
     @IntRange(from = 0, to = 7)
-    private int getDownstreamTypesMask(@NonNull final String types) {
+    int getDownstreamTypesMask(@NonNull final String types) {
         int downstreamTypesMask = DOWNSTREAM_NONE;
         final String[] downstreams = types.split("\\|");
         for (String downstream : downstreams) {
-            if ("USB".equals(downstream.trim())) {
+            if (USB_DOWNSTREAM.equals(downstream.trim())) {
                 downstreamTypesMask |= (1 << TETHERING_USB);
-            } else if ("WIFI".equals(downstream.trim())) {
+            } else if (WIFI_DOWNSTREAM.equals(downstream.trim())) {
                 downstreamTypesMask |= (1 << TETHERING_WIFI);
-            } else if ("BT".equals(downstream.trim())) {
+            } else if (BLUETOOTH_DOWNSTREAM.equals(downstream.trim())) {
                 downstreamTypesMask |= (1 << TETHERING_BLUETOOTH);
             }
         }
@@ -134,9 +180,8 @@
      *
      * @return {@link android.util.SparseArray} with downstream types and icon id info.
      */
-    @NonNull
-    private SparseArray<Integer> getIcons(@ArrayRes int id) {
-        final Resources res = mContext.getResources();
+    @VisibleForTesting
+    SparseArray<Integer> getIcons(@ArrayRes int id, @NonNull Resources res) {
         final String[] array = res.getStringArray(id);
         final SparseArray<Integer> icons = new SparseArray<>();
         for (String config : array) {
@@ -161,8 +206,9 @@
     }
 
     private boolean setupNotification() {
-        final Resources res = mContext.getResources();
-        final SparseArray<Integer> downstreamIcons = getIcons(R.array.tethering_notification_icons);
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final SparseArray<Integer> downstreamIcons =
+                getIcons(R.array.tethering_notification_icons, res);
 
         final int iconId = downstreamIcons.get(mDownstreamTypesMask, NO_ICON_ID);
         if (iconId == NO_ICON_ID) return NO_NOTIFY;
@@ -170,12 +216,12 @@
         final String title = res.getString(R.string.tethering_notification_title);
         final String message = res.getString(R.string.tethering_notification_message);
 
-        showNotification(iconId, title, message);
+        showNotification(iconId, title, message, ENABLE_NOTIFICATION_ID);
         return NOTIFY_DONE;
     }
 
     private void showNotification(@DrawableRes final int iconId, @NonNull final String title,
-            @NonNull final String message) {
+            @NonNull final String message, @NotificationId final int id) {
         final Intent intent = new Intent(Settings.ACTION_TETHER_SETTINGS);
         final PendingIntent pi = PendingIntent.getActivity(
                 mContext.createContextAsUser(UserHandle.CURRENT, 0),
@@ -193,6 +239,6 @@
                         .setContentIntent(pi)
                         .build();
 
-        mNotificationManager.notify(null /* tag */, NOTIFY_ID, notification);
+        mNotificationManager.notify(null /* tag */, id, notification);
     }
 }
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java b/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
index 020b32a..c5329d8 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
+++ b/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
@@ -33,6 +33,7 @@
 import android.net.ITetheringEventCallback;
 import android.net.NetworkCapabilities;
 import android.net.NetworkRequest;
+import android.net.NetworkStack;
 import android.net.TetheringRequestParcel;
 import android.net.dhcp.DhcpServerCallbacks;
 import android.net.dhcp.DhcpServingParamsParcel;
@@ -364,8 +365,7 @@
                     IBinder connector;
                     try {
                         final long before = System.currentTimeMillis();
-                        while ((connector = (IBinder) mContext.getSystemService(
-                                Context.NETWORK_STACK_SERVICE)) == null) {
+                        while ((connector = NetworkStack.getService()) == null) {
                             if (System.currentTimeMillis() - before > NETWORKSTACK_TIMEOUT_MS) {
                                 Log.wtf(TAG, "Timeout, fail to get INetworkStackConnector");
                                 return null;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitor.java b/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitor.java
index 2875f71..7ac7f5f 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitor.java
+++ b/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitor.java
@@ -244,7 +244,8 @@
         // Additionally, we log a message to aid in any subsequent debugging.
         mLog.i("requesting mobile upstream network: " + mobileUpstreamRequest);
 
-        cm().requestNetwork(mobileUpstreamRequest, mMobileNetworkCallback, 0, legacyType, mHandler);
+        cm().requestNetwork(mobileUpstreamRequest, 0, legacyType, mHandler,
+                mMobileNetworkCallback);
     }
 
     /** Release mobile network request. */
diff --git a/Tethering/tests/unit/src/android/net/ip/IpServerTest.java b/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
index 948266d..3106e0e 100644
--- a/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
+++ b/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
@@ -21,7 +21,7 @@
 import static android.net.TetheringManager.TETHERING_USB;
 import static android.net.TetheringManager.TETHERING_WIFI;
 import static android.net.TetheringManager.TETHERING_WIFI_P2P;
-import static android.net.TetheringManager.TETHER_ERROR_ENABLE_NAT_ERROR;
+import static android.net.TetheringManager.TETHER_ERROR_ENABLE_FORWARDING_ERROR;
 import static android.net.TetheringManager.TETHER_ERROR_NO_ERROR;
 import static android.net.TetheringManager.TETHER_ERROR_TETHER_IFACE_ERROR;
 import static android.net.dhcp.IDhcpServer.STATUS_SUCCESS;
@@ -448,7 +448,7 @@
         usbTeardownOrder.verify(mNetd, times(2)).interfaceSetCfg(
                 argThat(cfg -> IFACE_NAME.equals(cfg.ifName)));
         usbTeardownOrder.verify(mCallback).updateInterfaceState(
-                mIpServer, STATE_AVAILABLE, TETHER_ERROR_ENABLE_NAT_ERROR);
+                mIpServer, STATE_AVAILABLE, TETHER_ERROR_ENABLE_FORWARDING_ERROR);
         usbTeardownOrder.verify(mCallback).updateLinkProperties(
                 eq(mIpServer), mLinkPropertiesCaptor.capture());
         assertNoAddressesNorRoutes(mLinkPropertiesCaptor.getValue());
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/EntitlementManagerTest.java b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/EntitlementManagerTest.java
index 3a1d4a6..0a7850b 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/EntitlementManagerTest.java
+++ b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/EntitlementManagerTest.java
@@ -21,7 +21,7 @@
 import static android.net.TetheringManager.TETHERING_WIFI;
 import static android.net.TetheringManager.TETHER_ERROR_ENTITLEMENT_UNKNOWN;
 import static android.net.TetheringManager.TETHER_ERROR_NO_ERROR;
-import static android.net.TetheringManager.TETHER_ERROR_PROVISION_FAILED;
+import static android.net.TetheringManager.TETHER_ERROR_PROVISIONING_FAILED;
 import static android.provider.DeviceConfig.NAMESPACE_CONNECTIVITY;
 import static android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID;
 
@@ -284,11 +284,11 @@
         assertEquals(0, mEnMgr.uiProvisionCount);
         mEnMgr.reset();
         // 3. No cache value and ui entitlement check is needed.
-        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISION_FAILED;
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISIONING_FAILED;
         receiver = new ResultReceiver(null) {
             @Override
             protected void onReceiveResult(int resultCode, Bundle resultData) {
-                assertEquals(TETHER_ERROR_PROVISION_FAILED, resultCode);
+                assertEquals(TETHER_ERROR_PROVISIONING_FAILED, resultCode);
                 mCallbacklatch.countDown();
             }
         };
@@ -297,12 +297,13 @@
         callbackTimeoutHelper(mCallbacklatch);
         assertEquals(1, mEnMgr.uiProvisionCount);
         mEnMgr.reset();
-        // 4. Cache value is TETHER_ERROR_PROVISION_FAILED and don't need to run entitlement check.
+        // 4. Cache value is TETHER_ERROR_PROVISIONING_FAILED and don't need to run entitlement
+        // check.
         mEnMgr.fakeEntitlementResult = TETHER_ERROR_NO_ERROR;
         receiver = new ResultReceiver(null) {
             @Override
             protected void onReceiveResult(int resultCode, Bundle resultData) {
-                assertEquals(TETHER_ERROR_PROVISION_FAILED, resultCode);
+                assertEquals(TETHER_ERROR_PROVISIONING_FAILED, resultCode);
                 mCallbacklatch.countDown();
             }
         };
@@ -311,7 +312,7 @@
         callbackTimeoutHelper(mCallbacklatch);
         assertEquals(0, mEnMgr.uiProvisionCount);
         mEnMgr.reset();
-        // 5. Cache value is TETHER_ERROR_PROVISION_FAILED and ui entitlement check is needed.
+        // 5. Cache value is TETHER_ERROR_PROVISIONING_FAILED and ui entitlement check is needed.
         mEnMgr.fakeEntitlementResult = TETHER_ERROR_NO_ERROR;
         receiver = new ResultReceiver(null) {
             @Override
@@ -364,7 +365,7 @@
     public void verifyPermissionResult() {
         setupForRequiredProvisioning();
         mEnMgr.notifyUpstream(true);
-        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISION_FAILED;
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISIONING_FAILED;
         mEnMgr.startProvisioningIfNeeded(TETHERING_WIFI, true);
         mLooper.dispatchAll();
         assertFalse(mEnMgr.isCellularUpstreamPermitted());
@@ -380,15 +381,15 @@
     public void verifyPermissionIfAllNotApproved() {
         setupForRequiredProvisioning();
         mEnMgr.notifyUpstream(true);
-        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISION_FAILED;
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISIONING_FAILED;
         mEnMgr.startProvisioningIfNeeded(TETHERING_WIFI, true);
         mLooper.dispatchAll();
         assertFalse(mEnMgr.isCellularUpstreamPermitted());
-        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISION_FAILED;
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISIONING_FAILED;
         mEnMgr.startProvisioningIfNeeded(TETHERING_USB, true);
         mLooper.dispatchAll();
         assertFalse(mEnMgr.isCellularUpstreamPermitted());
-        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISION_FAILED;
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISIONING_FAILED;
         mEnMgr.startProvisioningIfNeeded(TETHERING_BLUETOOTH, true);
         mLooper.dispatchAll();
         assertFalse(mEnMgr.isCellularUpstreamPermitted());
@@ -403,7 +404,7 @@
         mLooper.dispatchAll();
         assertTrue(mEnMgr.isCellularUpstreamPermitted());
         mLooper.dispatchAll();
-        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISION_FAILED;
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISIONING_FAILED;
         mEnMgr.startProvisioningIfNeeded(TETHERING_USB, true);
         mLooper.dispatchAll();
         assertTrue(mEnMgr.isCellularUpstreamPermitted());
@@ -465,7 +466,7 @@
         assertEquals(0, mEnMgr.silentProvisionCount);
         mEnMgr.reset();
         // 6. switch upstream back to mobile again
-        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISION_FAILED;
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISIONING_FAILED;
         mEnMgr.notifyUpstream(true);
         mLooper.dispatchAll();
         assertEquals(0, mEnMgr.uiProvisionCount);
@@ -477,7 +478,7 @@
     public void testCallStopTetheringWhenUiProvisioningFail() {
         setupForRequiredProvisioning();
         verify(mEntitlementFailedListener, times(0)).onUiEntitlementFailed(TETHERING_WIFI);
-        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISION_FAILED;
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_PROVISIONING_FAILED;
         mEnMgr.notifyUpstream(true);
         mLooper.dispatchAll();
         mEnMgr.startProvisioningIfNeeded(TETHERING_WIFI, true);
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringNotificationUpdaterTest.kt b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringNotificationUpdaterTest.kt
new file mode 100644
index 0000000..b869491
--- /dev/null
+++ b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringNotificationUpdaterTest.kt
@@ -0,0 +1,262 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity.tethering
+
+import android.app.Notification
+import android.app.NotificationManager
+import android.content.Context
+import android.content.res.Resources
+import android.net.ConnectivityManager.TETHERING_BLUETOOTH
+import android.net.ConnectivityManager.TETHERING_USB
+import android.net.ConnectivityManager.TETHERING_WIFI
+import android.os.UserHandle
+import android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.filters.SmallTest
+import androidx.test.runner.AndroidJUnit4
+import com.android.internal.util.test.BroadcastInterceptingContext
+import com.android.networkstack.tethering.R
+import com.android.server.connectivity.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE
+import org.junit.Assert.assertEquals
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.ArgumentCaptor
+import org.mockito.ArgumentMatchers.any
+import org.mockito.ArgumentMatchers.anyInt
+import org.mockito.ArgumentMatchers.eq
+import org.mockito.Mock
+import org.mockito.Mockito.doReturn
+import org.mockito.Mockito.never
+import org.mockito.Mockito.reset
+import org.mockito.Mockito.times
+import org.mockito.Mockito.verifyZeroInteractions
+import org.mockito.Mockito.verify
+import org.mockito.MockitoAnnotations
+
+const val TEST_SUBID = 1
+const val WIFI_ICON_ID = 1
+const val USB_ICON_ID = 2
+const val BT_ICON_ID = 3
+const val GENERAL_ICON_ID = 4
+const val WIFI_MASK = 1 shl TETHERING_WIFI
+const val USB_MASK = 1 shl TETHERING_USB
+const val BT_MASK = 1 shl TETHERING_BLUETOOTH
+const val TITTLE = "Tethering active"
+const val MESSAGE = "Tap here to set up."
+const val TEST_TITTLE = "Hotspot active"
+const val TEST_MESSAGE = "Tap to set up hotspot."
+
+@RunWith(AndroidJUnit4::class)
+@SmallTest
+class TetheringNotificationUpdaterTest {
+    // lateinit used here for mocks as they need to be reinitialized between each test and the test
+    // should crash if they are used before being initialized.
+    @Mock private lateinit var mockContext: Context
+    @Mock private lateinit var notificationManager: NotificationManager
+    @Mock private lateinit var defaultResources: Resources
+    @Mock private lateinit var testResources: Resources
+
+    // lateinit for this class under test, as it should be reset to a different instance for every
+    // tests but should always be initialized before use (or the test should crash).
+    private lateinit var notificationUpdater: TetheringNotificationUpdater
+
+    private val ENABLE_ICON_CONFIGS = arrayOf(
+            "USB;android.test:drawable/usb", "BT;android.test:drawable/bluetooth",
+            "WIFI|BT;android.test:drawable/general", "WIFI|USB;android.test:drawable/general",
+            "USB|BT;android.test:drawable/general", "WIFI|USB|BT;android.test:drawable/general")
+
+    private inner class TestContext(c: Context) : BroadcastInterceptingContext(c) {
+        override fun createContextAsUser(user: UserHandle, flags: Int) =
+                if (user == UserHandle.ALL) mockContext else this
+    }
+
+    private inner class WrappedNotificationUpdater(c: Context) : TetheringNotificationUpdater(c) {
+        override fun getResourcesForSubId(context: Context, subId: Int) =
+                if (subId == TEST_SUBID) testResources else defaultResources
+    }
+
+    private fun setupResources() {
+        doReturn(ENABLE_ICON_CONFIGS).`when`(defaultResources)
+                .getStringArray(R.array.tethering_notification_icons)
+        doReturn(arrayOf("WIFI;android.test:drawable/wifi")).`when`(testResources)
+                .getStringArray(R.array.tethering_notification_icons)
+        doReturn(TITTLE).`when`(defaultResources).getString(R.string.tethering_notification_title)
+        doReturn(MESSAGE).`when`(defaultResources)
+                .getString(R.string.tethering_notification_message)
+        doReturn(TEST_TITTLE).`when`(testResources).getString(R.string.tethering_notification_title)
+        doReturn(TEST_MESSAGE).`when`(testResources)
+                .getString(R.string.tethering_notification_message)
+        doReturn(USB_ICON_ID).`when`(defaultResources)
+                .getIdentifier(eq("android.test:drawable/usb"), any(), any())
+        doReturn(BT_ICON_ID).`when`(defaultResources)
+                .getIdentifier(eq("android.test:drawable/bluetooth"), any(), any())
+        doReturn(GENERAL_ICON_ID).`when`(defaultResources)
+                .getIdentifier(eq("android.test:drawable/general"), any(), any())
+        doReturn(WIFI_ICON_ID).`when`(testResources)
+                .getIdentifier(eq("android.test:drawable/wifi"), any(), any())
+    }
+
+    @Before
+    fun setUp() {
+        MockitoAnnotations.initMocks(this)
+        val context = TestContext(InstrumentationRegistry.getInstrumentation().context)
+        doReturn(notificationManager).`when`(mockContext)
+                .getSystemService(Context.NOTIFICATION_SERVICE)
+        notificationUpdater = WrappedNotificationUpdater(context)
+        setupResources()
+    }
+
+    private fun Notification.title() = this.extras.getString(Notification.EXTRA_TITLE)
+    private fun Notification.text() = this.extras.getString(Notification.EXTRA_TEXT)
+
+    private fun verifyNotification(iconId: Int = 0, title: String = "", text: String = "") {
+        verify(notificationManager, never()).cancel(any(), anyInt())
+
+        val notificationCaptor = ArgumentCaptor.forClass(Notification::class.java)
+        verify(notificationManager, times(1))
+                .notify(any(), anyInt(), notificationCaptor.capture())
+
+        val notification = notificationCaptor.getValue()
+        assertEquals(iconId, notification.smallIcon.resId)
+        assertEquals(title, notification.title())
+        assertEquals(text, notification.text())
+
+        reset(notificationManager)
+    }
+
+    private fun verifyNoNotification() {
+        verify(notificationManager, times(1)).cancel(any(), anyInt())
+        verify(notificationManager, never()).notify(any(), anyInt(), any())
+
+        reset(notificationManager)
+    }
+
+    @Test
+    fun testNotificationWithDownstreamChanged() {
+        // Wifi downstream. No notification.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyNoNotification()
+
+        // Same downstream changed. Nothing happened.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyZeroInteractions(notificationManager)
+
+        // Wifi and usb downstreams. Show enable notification
+        notificationUpdater.onDownstreamChanged(WIFI_MASK or USB_MASK)
+        verifyNotification(GENERAL_ICON_ID, TITTLE, MESSAGE)
+
+        // Usb downstream. Still show enable notification.
+        notificationUpdater.onDownstreamChanged(USB_MASK)
+        verifyNotification(USB_ICON_ID, TITTLE, MESSAGE)
+
+        // No downstream. No notification.
+        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
+        verifyNoNotification()
+    }
+
+    @Test
+    fun testNotificationWithActiveDataSubscriptionIdChanged() {
+        // Usb downstream. Showed enable notification with default resource.
+        notificationUpdater.onDownstreamChanged(USB_MASK)
+        verifyNotification(USB_ICON_ID, TITTLE, MESSAGE)
+
+        // Same subId changed. Nothing happened.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(INVALID_SUBSCRIPTION_ID)
+        verifyZeroInteractions(notificationManager)
+
+        // Set test sub id. Clear notification with test resource.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
+        verifyNoNotification()
+
+        // Wifi downstream. Show enable notification with test resource.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyNotification(WIFI_ICON_ID, TEST_TITTLE, TEST_MESSAGE)
+
+        // No downstream. No notification.
+        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
+        verifyNoNotification()
+    }
+
+    private fun assertIconNumbers(number: Int, configs: Array<String?>) {
+        doReturn(configs).`when`(defaultResources)
+                .getStringArray(R.array.tethering_notification_icons)
+        assertEquals(number, notificationUpdater.getIcons(
+                R.array.tethering_notification_icons, defaultResources).size())
+    }
+
+    @Test
+    fun testGetIcons() {
+        assertIconNumbers(0, arrayOfNulls<String>(0))
+        assertIconNumbers(0, arrayOf(null, ""))
+        assertIconNumbers(3, arrayOf(
+                // These configurations are invalid with wrong strings or symbols.
+                ";", ",", "|", "|,;", "WIFI", "1;2", " U SB; ", "bt;", "WIFI;USB;BT", "WIFI|USB|BT",
+                "WIFI,BT,USB", " WIFI| |  | USB, test:drawable/test",
+                // This configuration is valid with two downstream types (USB, BT).
+                "USB|,,,,,|BT;drawable/test ",
+                // This configuration is valid with one downstream types (WIFI).
+                "     WIFI     ; android.test:drawable/xxx "))
+    }
+
+    @Test
+    fun testGetDownstreamTypesMask() {
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask(""))
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("1"))
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("WIFI_P2P"))
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("usb"))
+        assertEquals(WIFI_MASK, notificationUpdater.getDownstreamTypesMask(" WIFI "))
+        assertEquals(USB_MASK, notificationUpdater.getDownstreamTypesMask("USB | B T"))
+        assertEquals(BT_MASK, notificationUpdater.getDownstreamTypesMask(" WIFI: | BT"))
+        assertEquals(WIFI_MASK or USB_MASK,
+                notificationUpdater.getDownstreamTypesMask("1|2|USB|WIFI|BLUETOOTH||"))
+    }
+
+    @Test
+    fun testSetupRestrictedNotification() {
+        val title = InstrumentationRegistry.getInstrumentation().context.resources
+                .getString(R.string.disable_tether_notification_title)
+        val message = InstrumentationRegistry.getInstrumentation().context.resources
+                .getString(R.string.disable_tether_notification_message)
+        val disallowTitle = "Tether function is disallowed"
+        val disallowMessage = "Please contact your admin"
+        doReturn(title).`when`(defaultResources)
+                .getString(R.string.disable_tether_notification_title)
+        doReturn(message).`when`(defaultResources)
+                .getString(R.string.disable_tether_notification_message)
+        doReturn(disallowTitle).`when`(testResources)
+                .getString(R.string.disable_tether_notification_title)
+        doReturn(disallowMessage).`when`(testResources)
+                .getString(R.string.disable_tether_notification_message)
+
+        // User restrictions on. Show restricted notification.
+        notificationUpdater.notifyTetheringDisabledByRestriction()
+        verifyNotification(R.drawable.stat_sys_tether_general, title, message)
+
+        // User restrictions off. Clear notification.
+        notificationUpdater.tetheringRestrictionLifted()
+        verifyNoNotification()
+
+        // Set test sub id. No notification.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
+        verifyNoNotification()
+
+        // User restrictions on again. Show restricted notification with test resource.
+        notificationUpdater.notifyTetheringDisabledByRestriction()
+        verifyNotification(R.drawable.stat_sys_tether_general, disallowTitle, disallowMessage)
+    }
+}
\ No newline at end of file
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java
index d983fae..0980514 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java
+++ b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java
@@ -210,7 +210,6 @@
     private PhoneStateListener mPhoneStateListener;
     private InterfaceConfigurationParcel mInterfaceConfiguration;
 
-
     private class TestContext extends BroadcastInterceptingContext {
         TestContext(Context base) {
             super(base);
@@ -1073,13 +1072,15 @@
         when(mUserManager.getUserRestrictions()).thenReturn(newRestrictions);
 
         final Tethering.UserRestrictionActionListener ural =
-                new Tethering.UserRestrictionActionListener(mUserManager, mockTethering);
+                new Tethering.UserRestrictionActionListener(
+                        mUserManager, mockTethering, mNotificationUpdater);
         ural.mDisallowTethering = currentDisallow;
 
         ural.onUserRestrictionsChanged();
 
-        verify(mockTethering, times(expectedInteractionsWithShowNotification))
-                .untetherAll();
+        verify(mNotificationUpdater, times(expectedInteractionsWithShowNotification))
+                .notifyTetheringDisabledByRestriction();
+        verify(mockTethering, times(expectedInteractionsWithShowNotification)).untetherAll();
     }
 
     @Test
@@ -1087,7 +1088,7 @@
         final String[] emptyActiveIfacesList = new String[]{};
         final boolean currDisallow = false;
         final boolean nextDisallow = true;
-        final int expectedInteractionsWithShowNotification = 0;
+        final int expectedInteractionsWithShowNotification = 1;
 
         runUserRestrictionsChange(currDisallow, nextDisallow, emptyActiveIfacesList,
                 expectedInteractionsWithShowNotification);
@@ -1399,6 +1400,7 @@
         mPhoneStateListener.onActiveDataSubscriptionIdChanged(fakeSubId);
         final TetheringConfiguration newConfig = mTethering.getTetheringConfiguration();
         assertEquals(fakeSubId, newConfig.activeDataSubId);
+        verify(mNotificationUpdater, times(1)).onActiveDataSubscriptionIdChanged(eq(fakeSubId));
     }
 
     @Test
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitorTest.java b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitorTest.java
index 5ed75bf..7c98f62 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitorTest.java
+++ b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitorTest.java
@@ -212,8 +212,8 @@
         mUNM.updateMobileRequiresDun(true);
         mUNM.registerMobileNetworkRequest();
         verify(mCM, times(1)).requestNetwork(
-                any(NetworkRequest.class), any(NetworkCallback.class), anyInt(), anyInt(),
-                any(Handler.class));
+                any(NetworkRequest.class), anyInt(), anyInt(), any(Handler.class),
+                any(NetworkCallback.class));
 
         assertTrue(mUNM.mobileNetworkRequested());
         assertUpstreamTypeRequested(TYPE_MOBILE_DUN);
@@ -649,8 +649,8 @@
         }
 
         @Override
-        public void requestNetwork(NetworkRequest req, NetworkCallback cb,
-                int timeoutMs, int legacyType, Handler h) {
+        public void requestNetwork(NetworkRequest req,
+                int timeoutMs, int legacyType, Handler h, NetworkCallback cb) {
             assertFalse(allCallbacks.containsKey(cb));
             allCallbacks.put(cb, h);
             assertFalse(requested.containsKey(cb));