An error occurs when send SMS in background about telephony

[kakajansh]

@shounakmulay they are about sending SMS in background. We also encounter this problem. We have firebase configured, and when receive background notification we want to send SMS.

final FirebaseMessaging _firebaseMessaging = FirebaseMessaging();
final Telephony telephony = Telephony.instance;

@override
void initState() {
  initFirebase();
  super.initState();
}

initFirebase() async {
  await telephony.requestPhoneAndSmsPermissions;
  _firebaseMessaging.requestNotificationPermissions();
  _firebaseMessaging.subscribeToTopic('verify');
  _firebaseMessaging.configure(
    onBackgroundMessage: _onBackgroundMessage,
    onMessage: (Map<String, dynamic> notification) async {
      String phone = notification['data']['phone'];
      String message = notification['data']['body'];

      telephony.sendSms(to: phone, message: message);
    },
  );
}

onMessage fires only when app is open, and it works. But on onBackgroundMessage it throws above MissingPluginException error.

Future<dynamic> _onBackgroundMessage(
  Map<String, dynamic> notification,
) async {
  final String phone = notification['data']['phone'];
  final String message = notification['data']['body'];

  Telephony.instance.sendSms(to: phone, message: message);

  return Future<void>.value();
}

[shounakmulay]

@kakajansh Thanks for the explanation.
I guess I had an incorrect understand of the problem.
Will take a look and update here.

[dinahapuque]

I'm also getting this exception when using this package with WorkManager and AndroidAlarmManager ):

[shounakmulay]

Hey @cuongdl @dinahapuque

I was not able to reproduce this issue.
I could correctly receive SMS in background on an emulator as well as on a physical device.
Could you please provide a reproducible example that I can look into?

[dinahapuque]

Using AndroidAlertManager causes the same error:

(MissingPluginException(No implementation found for method sendSms on channel plugins.shounakmulay.com/foreground_sms_channel))

E.g:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  final int helloAlarmID = 0;
  await AndroidAlarmManager.initialize();

  runApp(App());

  await AndroidAlarmManager.periodic(
    const Duration(minutes: 1),
    helloAlarmID,
    sendSms,
    wakeup: true,
  );
}

Future<void> sendSms() async {
  try {
    Telephony.instance.sendSms(
        to: myPhone,
        message: myMessage;
  } catch (e) {
    print(e);
  }
}

[shivanshPurple]

Any updates!? I am also having the same problem when I try to send a SMS in the background by an android service

[tareqfaris]

I also have the same problem, is there a solution?

[shounakmulay]

I think the problem is that when the app is in background, the plugin initialization does not happen correctly on the android side.
Also if you app is still active in background, call the plugin from the background makes it loose the reference to the original method channel that is used as a communication bridge.

Maybe adding a backgroundInstance to call telephony methods from the background could be the solution. This way we don't make the original instance inactive and you can still continue using it once the app comes back to the foreground.

[shounakmulay]

This is fixed in v0.1.1.

Checkout https://github.com/shounakmulay/Telephony/tree/v0.1.1#executing-in-background

[kakajansh]

@shounakmulay For me it doesn't work with firebase background handler. But works when receiving sms in background.

This one works

telephony.listenIncomingSms(
  onNewMessage: (SmsMessage message) { ... },
  onBackgroundMessage: backgroundMessageHandler,
);

backgroundMessageHandler(SmsMessage message) async {
  Telephony.backgroundInstance.sendSms(to: "123456789", message: "Message from background");
}

This one throws Unhandled Exception: MissingPluginException(No implementation found for method sendSms on channel plugins.shounakmulay.com/foreground_sms_channel)

// foreground
FirebaseMessaging.onMessage.listen((RemoteMessage notification) async {
      ...
      Telephony.instance.sendSms(to: phone, message: msg);
});

// background
FirebaseMessaging.onBackgroundMessage(onBackgroundMessage);

Future<void> _onBackgroundMessage(RemoteMessage message) async {
  final String phone = message.data['phone'];
  final String body = message.data['body'];

  Telephony.backgroundInstance.sendSms(to: phone, message: body);
}

Could you please direct what is missing here. There are some other issues maybe related to this about mixing plugins.
How to make Flutter Workmanager plugin and Location plugin work together

[shounakmulay]

@kakajansh will take a look.
Would be great if you could give me some more info like does this happen only with the firebase messaging plugin or does it happen with other plugins as well?
Thanks.

[shounakmulay]

Closing this for now. Feel free to reopen with any updates.

[sharifka]

i have an error about using backgroundMessageHandler
Telephony.backgroundInstance.dialPhoneNumber('12345');
Telephony.instance.dialPhoneNumber('1234');
not works,but when used foreground is working fine.
what is the error,please any can helpe to fix this error.