Re-INVITES and Updates with SDP

When a specific session on the Access Session Border Controller (A-SBC) invokes the resources of the Transcoding Session Border Controller (T-SBC), the A-SBC continues to use the same T-SBC for the duration of the session. Anytime when the A-SBC receives a SIP message containing modified SDP, the A-SBC communicates the modification to the T-SBC.