diff --git a/src/com/android/phone/PhoneInterfaceManager.java b/src/com/android/phone/PhoneInterfaceManager.java
index 9780213..1a93823 100755
--- a/src/com/android/phone/PhoneInterfaceManager.java
+++ b/src/com/android/phone/PhoneInterfaceManager.java
@@ -5870,7 +5870,12 @@
     public boolean isRttEnabled(int subscriptionId) {
         final long identity = Binder.clearCallingIdentity();
         try {
-            return isRttSupported(subscriptionId);
+            boolean isRttSupported = isRttSupported(subscriptionId);
+            boolean isUserRttSettingOn = Settings.Secure.getInt(
+                    mApp.getContentResolver(), Settings.Secure.RTT_CALLING_MODE, 0) != 0;
+            boolean shouldIgnoreUserRttSetting = mApp.getCarrierConfigForSubId(subscriptionId)
+                    .getBoolean(CarrierConfigManager.KEY_IGNORE_RTT_MODE_SETTING_BOOL);
+            return isRttSupported && (isUserRttSettingOn || shouldIgnoreUserRttSetting);
         } finally {
             Binder.restoreCallingIdentity(identity);
         }
diff --git a/src/com/android/phone/settings/AccessibilitySettingsFragment.java b/src/com/android/phone/settings/AccessibilitySettingsFragment.java
index c9aa630..b665f4b 100644
--- a/src/com/android/phone/settings/AccessibilitySettingsFragment.java
+++ b/src/com/android/phone/settings/AccessibilitySettingsFragment.java
@@ -166,6 +166,17 @@
             int rttMode = mButtonRtt.isChecked() ? 1 : 0;
             Settings.Secure.putInt(mContext.getContentResolver(), Settings.Secure.RTT_CALLING_MODE,
                     rttMode);
+            // Update RTT config with IMS Manager if the always-on carrier config isn't set to true.
+            CarrierConfigManager configManager = (CarrierConfigManager) mContext.getSystemService(
+                            Context.CARRIER_CONFIG_SERVICE);
+            for (int subId : SubscriptionController.getInstance().getActiveSubIdList(true)) {
+                if (!configManager.getConfigForSubId(subId).getBoolean(
+                        CarrierConfigManager.KEY_IGNORE_RTT_MODE_SETTING_BOOL, false)) {
+                    int phoneId = SubscriptionController.getInstance().getPhoneId(subId);
+                    ImsManager imsManager = ImsManager.getInstance(getContext(), phoneId);
+                    imsManager.setRttEnabled(mButtonRtt.isChecked());
+                }
+            }
             return true;
         }