T-Lib-Initiated Consult Call Single EndPoint
There are some cases when it is not possible to use the normal means of initiating a consult call by setting the dialog of the main call on hold and creating a new dialog for the consult call. One such case involves a transfer initiated by a remote agent with a regular (non-VoIP) phone behind the media-gateway. In that case, a consult call can be initiated by "borrowing" the SIP Dialog from the main call and re-using it for the consult call.
The diagram below describes this kind of case. To provide Ring-Back to the agent during the progress of the call, the SIP Dialog is invited to Stream Manager, which will play a ring-back tone. If the consult call is finished by a TCompleteTransfer request (as shown in the diagram), that dialog will be terminated. If the agent decides to reconnect the call, the SIP Dialog will be returned to the main call and retrieved.