call method
Implementation
Future<void> call() async {
isOfferer = true;
if (pc == null) await initialize();
final offer = await pc!.createOffer();
await pc!.setLocalDescription(offer);
sendSignal(SignalingMessageType.offer, {
'sdp': offer.sdp,
'type': offer.type.name,
'connectionType': 'media',
});
}