Integrating VoIP into Flutter Apps: SIP Stack, CallKit, and Push Notifications

import 'package:dart_sip_ua/dart_sip_ua.dart';

class SipService implements SipUaHelperListener {
  final _helper = SipUaHelper();

  void init(String ext, String password, String serverWss) {
    final settings = UaSettings()
      ..webSocketUrl = serverWss  // e.g. wss://sip.celloip.com:8089/ws
      ..uri = 'sip:[email protected]'
      ..authorizationUser = ext
      ..password = password
      ..displayName = ext
      ..dtmfMode = DtmfMode.RFC2833;

    _helper.addSipUaHelperListener(this);
    _helper.start(settings);
  }

  @override
  void registrationStateChanged(RegistrationState state) {
    debugPrint('SIP status: ${state.state}');
  }

  @override
  void callStateChanged(Call call, CallState state) {
    if (state.state == CallStateEnum.CALL_INITIATION) {
      // Show incoming call UI via flutter_callkit_incoming
      showIncomingCallScreen(call);
    }
  }

  void makeCall(String destination) {
    _helper.call('sip:[email protected]',
        voiceonly: true);
  }
}

import 'package:flutter_callkit_incoming/flutter_callkit_incoming.dart';

Future<void> showIncomingCallScreen(String callerId, String uuid) async {
  final params = CallKitParams(
    id: uuid,
    nameCaller: callerId,
    appName: 'CelloIP',
    type: 0, // 0 = voice
    duration: 30000,
    android: AndroidParams(
      isCustomNotification: true,
      isShowLogo: false,
      ringtonePath: 'system_ringtone_default',
      backgroundColor: '#1BA8DC',
    ),
    ios: IOSParams(
      iconName: 'CallKitLogo',
      handleType: 'generic',
      supportsVideo: false,
      maximumCallGroups: 1,
      maximumCallsPerCallGroup: 1,
      ringtonePath: 'system_ringtone_default',
    ),
  );
  await FlutterCallkitIncoming.showCallkitIncoming(params);
}