This section will provide information on how a complete calling workflow can be set up using CometChat. We’ve built the complete workflow to help your users make calls, receive calls as well as accept/reject calls. Let us assume Alex to be the call initiator and Bob is the receiver.
  1. Alex initiates the call to Bob using the initiateCall() method.
  2. Bob now has two choices:
    1. Accept the call from Alex using the acceptCall() method.
    2. Reject the call from Alex using the rejectCall(“rejected”) method passing the status as rejected.
  3. In the meantime, Alex has the option to cancel the call he initiated to Bob using the rejectCall(“cancelled”) method passing the status as cancelled.
  4. If Bob accepts the call from Alex, both Alex and Bob need to call the startCall() method. Alex in the onOutgoingCallAccepted() method of the CallListener and Bob in the success obtained from the acceptCall() method and both will be connected to each other.

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Initiate Call

The initiateCall() method sends a call request to a user or a group. 
String receiverID = "UID";
String receiverType = CometChatConstants.RECEIVER_TYPE_USER;
String callType = CometChatConstants.CALL_TYPE_VIDEO;

Call call = Call(receiverUid: receiverID, receiverType: receiverType, type: callType);

CometChat.initiateCall(
  call,
  onSuccess: (Call call){
    debugPrint("Initiated");
  }, onError: (CometChatException e){
    debugPrint("Error: $e");
  }
);
This method takes an object of the Call class. The constructor for Call class takes the following parameters:
ParameterDescription
receiverIDThe UID or GUID of the recipient
receiverTypeThe type of the receiver viz. 1.CometChatConstants.RECEIVER_TYPE_USER 2.CometChatConstants.RECEIVER_TYPE_GROUP
callTypeThe type of the call viz. 1.CometChatConstants.CALL_TYPE_AUDIO 2.CometChatConstants.CALL_TYPE_VIDEO
On successful initialization, a Call object is returned with the details of the call including a unique session ID for the call.

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Receive Calls

For every activity you wish to receive the call events in, you need to register the CallListener listener using the addCallListener() method. 
import 'package:cometchat/cometchat_sdk.dart';

class YourClassName extends State<YourClassName> with CallListener {
@override
void initState() {
    CometChat.addCallListener(listenerId, this);  //Add listener
}

@override
void dispose() {
  super.dispose();
		CometChat.removeCallListener(listenerId); //Remove listener
}

@override
void onIncomingCallCancelled(Call call) {
  super.onIncomingCallCancelled(call);
  debugPrint("onIncomingCallCancelled");
}

@override
void onIncomingCallReceived(Call call) {
  super.onIncomingCallReceived(call);
  debugPrint("onIncomingCallReceived");
}

@override
void onOutgoingCallAccepted(Call call) {
  super.onOutgoingCallAccepted(call);
  debugPrint("onOutgoingCallAccepted");
}

@override
void onOutgoingCallRejected(Call call) {
  super.onOutgoingCallRejected(call);
  debugPrint("onOutgoingCallRejected");
}

@override
void onCallEndedMessageReceived(Call call) {
  super.onCallEndedMessageReceived(call);
  debugPrint("onCallEndedMessageReceived");
}
}
ParametrerDescription
listenerIDAn ID that uniquely identifies that listener. We recommend using the activity or fragment name
We recommend you remove the listener once the activity or fragment is not in use. 
String listenerId = "UNIQUE_LISTENER_ID";

CometChat.removeCallListener(listenerId);
As mentioned in the Overview section, Once the call is initiated, there are three options that can be possible:
  1. The receiver of the call accepts the call.
  2. The receiver of the call rejects the call.
  3. The initiator of the call cancels the call.
Please find below how these three scenarios can be implemented:

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Accept the Incoming Call

Once you have received an incoming call from a user or in any group, to accept the call using the acceptCall() method. 
String sessionID = "SESSION_ID";

CometChat.acceptCall(
  sessionId!,
  onSuccess: (Call call){
    debugPrint("Accepted");
  }, onError: (CometChatException e){
    debugPrint("Error: ${e.message}");
  }
);
ParameterDescription
sessionIDThe unique session ID available in the Call object

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Reject the Incoming Call

To reject the incoming call once it is received using the rejectCall() method. 
String sessionID = "SESSION_ID";
String status = CometChatConstants.CALL_STATUS_REJECTED;

CometChat.rejectCall(
  sessionId!,
		status,
  onSuccess: (Call call){
    debugPrint("Rejected");
  }, onError: (CometChatException e){
    debugPrint("Error: ${e.message}");
  }
);
ParameterDescription
sessionIDThe unique session ID available in the Call object
statusReason for rejection of the call
Here the status needs to be set as CometChatConstants.CALL_STATUS_REJECTED as the call is being rejected by the receiver of the call.

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Cancel the Outgoing Call

In the case where the initiator wishes to cancel the call, use the same above rejectCall() method and just pass the status to the rejectCall() method as CometChatConstants.CALL_STATUS_CANCELLED

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Start a Call

Once the call request is sent and the receiver has accepted the call, both the initiator and the receiver need to call the startSession() method.