SIP REFER Re-Invite for Call Leg SDP Renegotiation

Enhancing the original implementation of SIP REFER termination introduced in Release S-C6.0.0, this change to Oracle Communications Session Border Controller behavior allows for SDP renegotiation between both parties of a transferred call.

Scenario

In a call transfer initiated by SIP REFER, a call is established between two user agents, UA-A and UA-B. UA-B then sends a REFER request to transfer the call to UA-C. The challenge is that UA-A and UA-B had already been communicating using mutually agreed-on codec, while UA-C might not be using an entirely different codec.

To solve this problem, the Oracle Communications Session Border Controller causes a new SIP session and new media session to be created between UA-A and UA-C. The Oracle Communications Session Border Controller removes any resources allocated for use between UA-A and UA-B, and then severs its connection with UA-B. The session between UA-A and UA-C continues.