public void addIncomingCallListener(
     ClientIdentity identity, SDPType type, IncomingCallListener listener) {
   incomingCallListenerHolder.addListener(listener, identity, type);
 }
 public void addIncomingCallListener(
     ClientIdentity clientIdentity, IncomingCallListener listener) {
   incomingCallListenerHolder.addListener(listener, clientIdentity);
 }
 public void addIncomingCallListener(final IncomingCallListener listener) {
   incomingCallListenerHolder.addListener(listener);
 }
 public void addIncomingCallListener(SDPType sdpType, final IncomingCallListener listener) {
   incomingCallListenerHolder.addListener(listener, sdpType);
 }
 public void addDialogStateListener(
     final Dialog dialog, final DialogStateListener<BaseSipMessage> listener) {
   dialogStateListenerHolder.addListener(listener, dialog);
 }