invite method
void
invite()
Implementation
void invite(
String callerName,
String callerNumber,
String destinationNumber,
String clientState,
String callId,
String telnyxSessionId,
Map<String, String> customHeaders) async {
var sessionId = _selfId;
Session session = await _createSession(null,
peerId: "0", sessionId: sessionId, media: "audio");
_sessions[sessionId] = session;
_createOffer(session, "audio", callerName, callerNumber, destinationNumber,
clientState, callId, telnyxSessionId, customHeaders);
onCallStateChange?.call(session, CallState.newCall);
}