diff --git a/src/com/android/phone/PhoneInterfaceManager.java b/src/com/android/phone/PhoneInterfaceManager.java
index 722f97b..3bad155 100755
--- a/src/com/android/phone/PhoneInterfaceManager.java
+++ b/src/com/android/phone/PhoneInterfaceManager.java
@@ -9933,7 +9933,7 @@
     @Override
     public void sendDeviceToDeviceMessage(int message, int value) {
         TelephonyPermissions.enforceShellOnly(Binder.getCallingUid(),
-                "setCarrierSingleRegistrationEnabledOverride");
+                "sendDeviceToDeviceMessage");
         enforceModifyPermission();
 
         final long identity = Binder.clearCallingIdentity();
@@ -9950,6 +9950,29 @@
         }
     }
 
+    /**
+     * Sets the specified device to device transport active.
+     * @param transport The transport to set active.
+     */
+    @Override
+    public void setActiveDeviceToDeviceTransport(@NonNull String transport) {
+        TelephonyPermissions.enforceShellOnly(Binder.getCallingUid(),
+                "setActiveDeviceToDeviceTransport");
+        enforceModifyPermission();
+
+        final long identity = Binder.clearCallingIdentity();
+        try {
+            TelephonyConnectionService service =
+                    TelecomAccountRegistry.getInstance(null).getTelephonyConnectionService();
+            if (service == null) {
+                Rlog.e(LOG_TAG, "setActiveDeviceToDeviceTransport: not in a call.");
+                return;
+            }
+            service.setActiveDeviceToDeviceTransport(transport);
+        } finally {
+            Binder.restoreCallingIdentity(identity);
+        }
+    }
 
     /**
      * Gets the config of RCS VoLTE single registration enabled for the device.
diff --git a/src/com/android/phone/TelephonyShellCommand.java b/src/com/android/phone/TelephonyShellCommand.java
index 79dfbcf..ea12984 100644
--- a/src/com/android/phone/TelephonyShellCommand.java
+++ b/src/com/android/phone/TelephonyShellCommand.java
@@ -113,6 +113,7 @@
 
     private static final String D2D_SUBCOMMAND = "d2d";
     private static final String D2D_SEND = "send";
+    private static final String D2D_TRANSPORT = "transport";
 
     private static final String RCS_UCE_COMMAND = "uce";
     private static final String UCE_GET_EAB_CONTACT = "get-eab-contact";
@@ -271,6 +272,9 @@
                         MESSAGE_DEVICE_BATTERY_STATE));
         pw.println("    Type: " + MESSAGE_DEVICE_NETWORK_COVERAGE + " - "
                 + Communicator.messageToString(MESSAGE_DEVICE_NETWORK_COVERAGE));
+        pw.println("  d2d transport TYPE");
+        pw.println("    Forces the specified D2D transport TYPE to be active.  Use the");
+        pw.println("    short class name of the transport; i.e. DtmfTransport or RtpTransport.");
     }
 
     private void onHelpIms() {
@@ -634,6 +638,9 @@
             case D2D_SEND: {
                 return handleD2dSendCommand();
             }
+            case D2D_TRANSPORT: {
+                return handleD2dTransportCommand();
+            }
         }
 
         return -1;
@@ -641,11 +648,9 @@
 
     private int handleD2dSendCommand() {
         PrintWriter errPw = getErrPrintWriter();
-        String opt;
         int messageType = -1;
         int messageValue = -1;
 
-
         String arg = getNextArg();
         if (arg == null) {
             onHelpD2D();
@@ -681,6 +686,25 @@
         return 0;
     }
 
+    private int handleD2dTransportCommand() {
+        PrintWriter errPw = getErrPrintWriter();
+
+        String arg = getNextArg();
+        if (arg == null) {
+            onHelpD2D();
+            return 0;
+        }
+
+        try {
+            mInterface.setActiveDeviceToDeviceTransport(arg);
+        } catch (RemoteException e) {
+            Log.w(LOG_TAG, "d2d transport error: " + e.getMessage());
+            errPw.println("Exception: " + e.getMessage());
+            return -1;
+        }
+        return 0;
+    }
+
     // ims set-ims-service
     private int handleImsSetServiceCommand() {
         PrintWriter errPw = getErrPrintWriter();
diff --git a/src/com/android/services/telephony/TelephonyConnection.java b/src/com/android/services/telephony/TelephonyConnection.java
index 7a59908..da41077 100755
--- a/src/com/android/services/telephony/TelephonyConnection.java
+++ b/src/com/android/services/telephony/TelephonyConnection.java
@@ -28,6 +28,7 @@
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Message;
+import android.os.Messenger;
 import android.os.PersistableBundle;
 import android.telecom.BluetoothCallQualityReport;
 import android.telecom.CallAudioState;
@@ -95,6 +96,7 @@
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Executors;
+import java.util.stream.Collectors;
 
 /**
  * Base class for CDMA and GSM connections.
@@ -133,6 +135,7 @@
     private static final int MSG_ON_CONNECTION_EVENT = 19;
     private static final int MSG_REDIAL_CONNECTION_CHANGED = 20;
     private static final int MSG_REJECT = 21;
+    private static final int MSG_DTMF_DONE = 22;
 
     private static final String JAPAN_COUNTRY_CODE_WITH_PLUS_SIGN = "+81";
     private static final String JAPAN_ISO_COUNTRY_CODE = "JP";
@@ -303,6 +306,9 @@
                     int rejectReason = (int) msg.obj;
                     reject(rejectReason);
                     break;
+                case MSG_DTMF_DONE:
+                    Log.i(this, "MSG_DTMF_DONE");
+                    break;
 
                 case MSG_SET_CALL_RADIO_TECH:
                     int vrat = (int) msg.obj;
@@ -341,6 +347,8 @@
         }
     };
 
+    private final Messenger mHandlerMessenger = new Messenger(mHandler);
+
     /**
      * Handles {@link SuppServiceNotification}s pertinent to Telephony.
      * @param ssn the notification.
@@ -510,7 +518,7 @@
 
         @Override
         public void onStateChanged(android.telecom.Connection c, int state) {
-            mCommunicator.onStateChanged(c, state);
+            mCommunicator.onStateChanged(c.getTelecomCallId(), state);
         }
     }
 
@@ -742,6 +750,15 @@
                     extensionData.size());
             mRtpTransport.onRtpHeaderExtensionsReceived(extensionData);
         }
+
+        @Override
+        public void onReceivedDtmfDigit(char digit) {
+            if (mDtmfTransport == null) {
+                return;
+            }
+            Log.i(this, "onReceivedDtmfDigit: digit=%c", digit);
+            mDtmfTransport.onDtmfReceived(digit);
+        }
     };
 
     private TelephonyConnectionService mTelephonyConnectionService;
@@ -2351,7 +2368,7 @@
             }
 
             if (mCommunicator != null) {
-                mCommunicator.onStateChanged(this, getState());
+                mCommunicator.onStateChanged(getTelecomCallId(), getState());
             }
         }
     }
@@ -3284,13 +3301,18 @@
     private void maybeConfigureDeviceToDeviceCommunication() {
         if (!getPhone().getContext().getResources().getBoolean(
                 R.bool.config_use_device_to_device_communication)) {
-            Log.d(this, "maybeConfigureDeviceToDeviceCommunication: not using D2D.");
+            Log.i(this, "maybeConfigureDeviceToDeviceCommunication: not using D2D.");
             return;
         }
         if (!isImsConnection()) {
-            Log.d(this, "maybeConfigureDeviceToDeviceCommunication: not an IMS connection.");
+            Log.i(this, "maybeConfigureDeviceToDeviceCommunication: not an IMS connection.");
             return;
         }
+        if (mTreatAsEmergencyCall || mIsNetworkIdentifiedEmergencyCall) {
+            Log.i(this, "maybeConfigureDeviceToDeviceCommunication: emergency call; no D2D");
+            return;
+        }
+
         // Implement abstracted out RTP functionality the RTP transport depends on.
         RtpAdapter rtpAdapter = new RtpAdapter() {
             @Override
@@ -3309,8 +3331,11 @@
                 if (!isImsConnection()) {
                     Log.w(TelephonyConnection.this, "sendRtpHeaderExtensions: not an ims conn.");
                 }
-                Log.d(TelephonyConnection.this, "sendRtpHeaderExtensions: sending %d messages",
-                        rtpHeaderExtensions.size());
+
+                Log.i(TelephonyConnection.this, "sendRtpHeaderExtensions: sending: %s",
+                        rtpHeaderExtensions.stream()
+                                .map(r -> r.toString())
+                                .collect(Collectors.joining(",")));
                 ImsPhoneConnection originalConnection =
                         (ImsPhoneConnection) mOriginalConnection;
                 originalConnection.sendRtpHeaderExtensions(rtpHeaderExtensions);
@@ -3322,10 +3347,12 @@
             if (!isImsConnection()) {
                 Log.w(TelephonyConnection.this, "sendDtmf: not an ims conn.");
             }
-            Log.d(TelephonyConnection.this, "sendDtmf: send digit %c", digit);
+            Log.i(TelephonyConnection.this, "sendDtmf: send digit %c", digit);
             ImsPhoneConnection originalConnection =
                     (ImsPhoneConnection) mOriginalConnection;
-            originalConnection.getImsCall().sendDtmf(digit, null /* result msg not needed */);
+            Message dtmfComplete = mHandler.obtainMessage(MSG_DTMF_DONE);
+            dtmfComplete.replyTo = mHandlerMessenger;
+            originalConnection.getImsCall().sendDtmf(digit, dtmfComplete);
         };
         ContentResolver cr = getPhone().getContext().getContentResolver();
         mDtmfTransport = new DtmfTransport(dtmfAdapter, new Timeouts.Adapter(cr),
diff --git a/src/com/android/services/telephony/TelephonyConnectionService.java b/src/com/android/services/telephony/TelephonyConnectionService.java
index 219c782..0803178 100644
--- a/src/com/android/services/telephony/TelephonyConnectionService.java
+++ b/src/com/android/services/telephony/TelephonyConnectionService.java
@@ -2538,6 +2538,26 @@
        });
     }
 
+    /**
+     * Overrides the current D2D transport, forcing the specified one to be active.  Used for test.
+     * @param transport The class simple name of the transport to make active.
+     */
+    public void setActiveDeviceToDeviceTransport(@NonNull String transport) {
+        getAllConnections().stream()
+                .filter(f -> f instanceof TelephonyConnection)
+                .forEach(t -> {
+                    TelephonyConnection tc = (TelephonyConnection) t;
+                    Communicator c = tc.getCommunicator();
+                    if (c == null) {
+                        Log.w(this, "setActiveDeviceToDeviceTransport: D2D not enabled");
+                        return;
+                    }
+                    Log.i(this, "setActiveDeviceToDeviceTransport: callId=%s, set to: %s",
+                            tc.getTelecomCallId(), transport);
+                    c.setTransportActive(transport);
+                });
+    }
+
     private PhoneAccountHandle adjustAccountHandle(Phone phone,
             PhoneAccountHandle origAccountHandle) {
         int origSubId = PhoneUtils.getSubIdForPhoneAccountHandle(origAccountHandle);