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This chapter provides an overview of the libraries and protocols used for third party call control 
(3PCC) and describes how to use the Dialogic

®

 Global Call API to perform certain third party call 

control operations in a SIP environment. Topics include:

This section provides an overview of third party call control, along with brief descriptions of the 
libraries and protocols required to support third party call control. The following topics are 
presented in this section:

Third party call control enables one entity (for example, a third party call controller) to create, 
modify, or terminate a media session between two or more endpoints. Call control signaling and 
media exchange are separated and independently managed.

The key attributes of third party call control are:

A distinct third party call controller initiates the session. 

The third party call controller initiates communications via a SIP signaling interface to each of 
the endpoints involved in the session. 

The endpoints do not need to directly establish signaling interfaces between one another; 
instead, they have a signaling relationship with the third party call controller. 

The third party call controller does not serve as an endpoint for the media stream; the media 
stream flows between the two endpoints.