Operation is unstable when disconnecting and reconnecting Wi-Fi during a call, or when disconnecting Wi-Fi and connecting to mobile (4G/5G)

[ryotasakurada]

Describe the bug
I am using dart-sip-ua to make calls via Asterisk.
Because the behavior of the mobile device is unstable when changing networks, I am reporting this.

background:
The device is connected to Asterisk using a client-server method, not a P2P connection.
I am using ICE to send the results to Asterisk to make WebRTC calls.

To Reproduce
Steps to reproduce the behavior:
The behavior is unstable on both iOS and Android, but it is particularly noticeable on Android, so I will give an example of an Android device.

1. Start a call between two devices (device <-> Asterisk <-> device)
2. Disconnect the Android device's Wi-Fi (It is assumed that there is no 4G connection)
   2-1. The call is disconnected at this point
3. Reconnect the Android device's Wi-Fi. Of course, the call has already ended, so it cannot be resumed.

Expected behavior
If you are making a SIP call, the call should resume when you reconnect to Wi-Fi (confirmed with Zoiper SIP Client)

System Infomation()
Flutter SDK Version: 3.22.2
Target OS and Version: Android 10,11,12
sip-ua-dart version: 0.6.0

[viniciusoliverrs]

I have the same problem. Any solution?

[reduxdj]

The solution is rather complicated, and requires a change in _iceRestart and the transport, first comment out the terminate call in there, set _iceRestarts true in the options under mandatory

Overload the transport library, ours looks like this, we use connectivity plus and a dart:io to check when we have wifi/mobile and can make a successful lookup of google's address.

when you have a successful internet restored, call renegoation({ useUpdate: true}, this forces a reconnection to your webrtc connection, so expose this function from transport.dart to your session...

Somethiing like this:

  bool send(dynamic data) {
    // logger.d('send()');

    if (!isConnected()) {
      logger.e('unable to send message, transport is not connected. Current state is $status', stackTrace: StackTraceNJ());
      return false;
    }
    bool isOutgoing = data is OutgoingRequest;

    String message = data.toString();
    //logger.d('sending message:\n\n$message\n');
    if (isOutgoing) {
      OutgoingRequest outgoing = data;
      if (outgoing.method == SipMethod.UPDATE) {
        _reconnect(() {
          socket.send(message);
          disableDisconnectionEvent = false;
        });
        return true;
      }
    }

    return socket.send(message);
  }

[aberutti-convorelay]

Hi @reduxdj. Could you elaborate a little bit more on your response? I'm having the same issue but with desktop flutter. When turning off/on the WiFi at a certain timing RTCIceConnectionStateDisconnected is triggered and _iceRestart() is being called but the re-INVITE is not reaching the server although the re-registering was successful and they are hitting the request timeout, I've implemented a retry policy but no luck so far, invites are never reaching the sip server. I really appreciate any help you can provide.