SDP Offer Example

The following abbreviated call flow diagram sets up a media-over-TCP flow. Observe that the caller listens for audio over TCP on 172.16.0.10:10000, as described in the SDP offer (1). The Oracle® Enterprise Session Border Controller re-writes the m and c lines in the SDP offer to reflect that it is listening for audio over TCP on its egress interface at 192.168.0.1:10000 (3). The Oracle® Enterprise Session Border Controller then forwards the SIP invite to the callee.

The SIP callee responds with an SDP answer in a 200 OK message. The callee indicates it is listening for the audio over TCP media on 192.168.0.10:10001 (6). The Oracle® Enterprise Session Border Controller re-writes the m and c lines in the SDP answer to reflect that it is listening for audio over TCP on the call's ingress interface at 172.16.0.1:10001 (7). The Oracle® Enterprise Session Border Controller then forwards the SIP invite to the caller.

All interfaces involved with the end-to-end TCP flow have now established their listening IP address and port pairs.