diff --git a/res/values-zh-rCN/strings.xml b/res/values-zh-rCN/strings.xml
index 713063c..c1f3332 100644
--- a/res/values-zh-rCN/strings.xml
+++ b/res/values-zh-rCN/strings.xml
@@ -441,7 +441,7 @@
     <string name="deleting_fdn_contact" msgid="5669163206349319969">"正在删除固定拨号联系人..."</string>
     <string name="fdn_contact_deleted" msgid="7154162327112259569">"已删除固定拨号联系人。"</string>
     <string name="pin2_invalid" msgid="5470854099230755944">"固定拨号未更新，因为输入的 PIN 码有误。"</string>
-    <string name="fdn_invalid_number" msgid="2062898833049589309">"未能更新 FDN，因为号码超过 20 位数。"</string>
+    <string name="fdn_invalid_number" msgid="2062898833049589309">"未能更新 FDN，因为号码超过 <xliff:g id="FDN_NUMBER_LIMIT_LENGTH">%d</xliff:g> 位数。"</string>
     <string name="pin2_or_fdn_invalid" msgid="6025144083384701197">"固定拨号未更新。PIN2 码有误，或电话号码遭拒。"</string>
     <string name="fdn_failed" msgid="540018079008319747">"固定拨号操作失败。"</string>
     <string name="simContacts_emptyLoading" msgid="2203331234764498011">"正在从SIM卡读取..."</string>
diff --git a/res/values-zh-rTW/strings.xml b/res/values-zh-rTW/strings.xml
index 606f059..679ecdd 100644
--- a/res/values-zh-rTW/strings.xml
+++ b/res/values-zh-rTW/strings.xml
@@ -443,7 +443,7 @@
     <string name="deleting_fdn_contact" msgid="5669163206349319969">"正在刪除固定撥號…"</string>
     <string name="fdn_contact_deleted" msgid="7154162327112259569">"已刪除固定撥號。"</string>
     <string name="pin2_invalid" msgid="5470854099230755944">"您所輸入的 PIN 不正確，因此未更新 FDN。"</string>
-    <string name="fdn_invalid_number" msgid="2062898833049589309">"固定撥號的號碼超過 20 位數，因此無法更新。"</string>
+    <string name="fdn_invalid_number" msgid="2062898833049589309">"固定撥號的號碼超過 <xliff:g id="FDN_NUMBER_LIMIT_LENGTH">%d</xliff:g> 位數，因此無法更新。"</string>
     <string name="pin2_or_fdn_invalid" msgid="6025144083384701197">"未更新 FDN。可能是因為 PIN2 碼不正確或電話號碼遭拒。"</string>
     <string name="fdn_failed" msgid="540018079008319747">"FDN 操作失敗。"</string>
     <string name="simContacts_emptyLoading" msgid="2203331234764498011">"正在從 SIM 卡讀取…"</string>
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 1fc2d6f..dfec1d8 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -977,7 +977,7 @@
     <!-- FDN settings: error message displayed in a popup (toast) -->
     <string name="pin2_invalid">FDN wasn\'t updated because you typed an incorrect PIN.</string>
     <!-- FDN settings: error message displayed in a popup (toast) -->
-    <string name="fdn_invalid_number">FDN wasn\'t updated because the number exceeds 20 digits.</string>
+    <string name="fdn_invalid_number">FDN wasn\'t updated because the number exceeds <xliff:g id="FDN_NUMBER_LIMIT_LENGTH">%d</xliff:g> digits.</string>
     <!-- FDN settings: error message displayed in a popup (toast), when the entered
          FDN number was inappropriate, OR, PIN2 the user entered was incorrect.
          Because of API restriction, there's no way to determine which is the exact
diff --git a/src/com/android/phone/PhoneInterfaceManager.java b/src/com/android/phone/PhoneInterfaceManager.java
index 8847e17..b122743 100755
--- a/src/com/android/phone/PhoneInterfaceManager.java
+++ b/src/com/android/phone/PhoneInterfaceManager.java
@@ -99,6 +99,7 @@
 import android.telephony.gsm.GsmCellLocation;
 import android.telephony.ims.ImsException;
 import android.telephony.ims.ProvisioningManager;
+import android.telephony.ims.RegistrationManager;
 import android.telephony.ims.aidl.IImsCapabilityCallback;
 import android.telephony.ims.aidl.IImsConfig;
 import android.telephony.ims.aidl.IImsConfigCallback;
@@ -2951,6 +2952,74 @@
         }
     }
 
+    /**
+     * Get the IMS service registration state for the MmTelFeature associated with this sub id.
+     */
+    @Override
+    public void getImsMmTelRegistrationState(int subId, IIntegerConsumer consumer) {
+        enforceReadPrivilegedPermission("getImsMmTelRegistrationState");
+        if (!ImsManager.isImsSupportedOnDevice(mApp)) {
+            throw new ServiceSpecificException(ImsException.CODE_ERROR_UNSUPPORTED_OPERATION,
+                    "IMS not available on device.");
+        }
+        final long token = Binder.clearCallingIdentity();
+        try {
+            Phone phone = getPhone(subId);
+            if (phone == null) {
+                Log.w(LOG_TAG, "getImsMmTelRegistrationState: called with an invalid subscription '"
+                        + subId + "'");
+                throw new ServiceSpecificException(ImsException.CODE_ERROR_INVALID_SUBSCRIPTION);
+            }
+            phone.getImsRegistrationState(regState -> {
+                try {
+                    consumer.accept((regState == null)
+                            ? RegistrationManager.REGISTRATION_STATE_NOT_REGISTERED : regState);
+                } catch (RemoteException e) {
+                    // Ignore if the remote process is no longer available to call back.
+                    Log.w(LOG_TAG, "getImsMmTelRegistrationState: callback not available.");
+                }
+            });
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+    }
+
+    /**
+     * Get the transport type for the IMS service registration state.
+     */
+    @Override
+    public void getImsMmTelRegistrationTransportType(int subId, IIntegerConsumer consumer) {
+        enforceReadPrivilegedPermission("getImsMmTelRegistrationTransportType");
+        if (!ImsManager.isImsSupportedOnDevice(mApp)) {
+            throw new ServiceSpecificException(ImsException.CODE_ERROR_UNSUPPORTED_OPERATION,
+                    "IMS not available on device.");
+        }
+        final long token = Binder.clearCallingIdentity();
+        try {
+            Phone phone = getPhone(subId);
+            if (phone == null) {
+                Log.w(LOG_TAG, "getImsMmTelRegistrationState: called with an invalid subscription '"
+                        + subId + "'");
+                throw new ServiceSpecificException(ImsException.CODE_ERROR_INVALID_SUBSCRIPTION);
+            }
+            phone.getImsRegistrationTech(regTech -> {
+                // Convert registration tech from ImsRegistrationImplBase -> RegistrationManager
+                int regTechConverted = (regTech == null)
+                        ? ImsRegistrationImplBase.REGISTRATION_TECH_NONE : regTech;
+                regTechConverted = RegistrationManager.IMS_REG_TO_ACCESS_TYPE_MAP.get(
+                        regTechConverted);
+                try {
+                    consumer.accept(regTechConverted);
+                } catch (RemoteException e) {
+                    // Ignore if the remote process is no longer available to call back.
+                    Log.w(LOG_TAG, "getImsMmTelRegistrationState: callback not available.");
+                }
+            });
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+    }
+
     @Override
     public void registerMmTelCapabilityCallback(int subId, IImsCapabilityCallback c)
             throws RemoteException {
diff --git a/src/com/android/phone/settings/fdn/EditFdnContactScreen.java b/src/com/android/phone/settings/fdn/EditFdnContactScreen.java
index c358e27..0eda140 100644
--- a/src/com/android/phone/settings/fdn/EditFdnContactScreen.java
+++ b/src/com/android/phone/settings/fdn/EditFdnContactScreen.java
@@ -29,6 +29,7 @@
 import android.net.Uri;
 import android.os.Bundle;
 import android.os.Handler;
+import android.os.PersistableBundle;
 import android.provider.ContactsContract.CommonDataKinds;
 import android.telephony.PhoneNumberUtils;
 import android.text.Editable;
@@ -52,6 +53,7 @@
 import com.android.phone.PhoneGlobals;
 import com.android.phone.R;
 import com.android.phone.SubscriptionInfoHelper;
+import android.telephony.CarrierConfigManager;
 
 /**
  * Activity to let the user add or edit an FDN contact.
@@ -100,6 +102,7 @@
     }
     /** flag to track saving state */
     private boolean mDataBusy;
+    private int mFdnNumberLimitLength = 20;
 
     @Override
     protected void onCreate(Bundle icicle) {
@@ -111,6 +114,17 @@
         setContentView(R.layout.edit_fdn_contact_screen);
         setupView();
         setTitle(mAddContact ? R.string.add_fdn_contact : R.string.edit_fdn_contact);
+        PersistableBundle b = null;
+        if (mSubscriptionInfoHelper.hasSubId()) {
+            b = PhoneGlobals.getInstance().getCarrierConfigForSubId(
+                    mSubscriptionInfoHelper.getSubId());
+        } else {
+            b = PhoneGlobals.getInstance().getCarrierConfig();
+        }
+        if (b != null) {
+            mFdnNumberLimitLength = b.getInt(
+                    CarrierConfigManager.KEY_FDN_NUMBER_LENGTH_LIMIT_INT);
+        }
 
         displayProgress(false);
     }
@@ -294,7 +308,7 @@
       * TODO: Fix this logic.
       */
      private boolean isValidNumber(String number) {
-         return (number.length() <= 20) && (number.length() > 0);
+         return (number.length() <= mFdnNumberLimitLength) && (number.length() > 0);
      }
 
 
@@ -397,7 +411,8 @@
         } else {
             if (DBG) log("handleResult: failed!");
             if (invalidNumber) {
-                showStatus(getResources().getText(R.string.fdn_invalid_number));
+                showStatus(getResources().getString(R.string.fdn_invalid_number,
+                        mFdnNumberLimitLength));
             } else {
                if (PhoneFactory.getDefaultPhone().getIccCard().getIccPin2Blocked()) {
                     showStatus(getResources().getText(R.string.fdn_enable_puk2_requested));
diff --git a/testapps/ImsTestService/src/com/android/phone/testapps/imstestapp/ImsRegistrationActivity.java b/testapps/ImsTestService/src/com/android/phone/testapps/imstestapp/ImsRegistrationActivity.java
index 4ee9355..139f8ac 100644
--- a/testapps/ImsTestService/src/com/android/phone/testapps/imstestapp/ImsRegistrationActivity.java
+++ b/testapps/ImsTestService/src/com/android/phone/testapps/imstestapp/ImsRegistrationActivity.java
@@ -24,6 +24,7 @@
 import android.telephony.ims.ImsException;
 import android.telephony.ims.ImsMmTelManager;
 import android.telephony.ims.ImsReasonInfo;
+import android.telephony.ims.RegistrationManager;
 import android.telephony.ims.stub.ImsRegistrationImplBase;
 import android.util.ArrayMap;
 import android.util.Log;
@@ -103,8 +104,8 @@
     }
 
 
-    private final ImsMmTelManager.RegistrationCallback mRegistrationCallback =
-            new ImsMmTelManager.RegistrationCallback() {
+    private final RegistrationManager.RegistrationCallback mRegistrationCallback =
+            new RegistrationManager.RegistrationCallback() {
 
         @Override
         public void onRegistered(int imsRadioTech) {
@@ -181,7 +182,7 @@
         try {
             mImsManager = ImsMmTelManager.createForSubscriptionId(
                     SubscriptionManager.getDefaultVoiceSubscriptionId());
-            mImsManager.registerImsRegistrationCallback(getMainExecutor(), mRegistrationCallback);
+            mImsManager.registerImsRegistrationCallback(mRegistrationCallback, getMainExecutor());
         } catch (IllegalArgumentException | ImsException e) {
             Log.w("ImsCallingActivity", "illegal subscription ID.");
         }