SIP Duplicate SDP Suppression

Using the strip-dup-sdp option in the SIP configuration, you can enable your Oracle® Enterprise Session Border Controller to suppress a duplicate SDP answer in the reliable responses (1xx and 2xx) in an INVITE transaction.

During INVITE transactions in certain networks, SDP answers in reliable provisional responses (1xx) can cause interoperability issues. This issue occurs when the UAS includes the SDP answer in subsequent 1xx responses or in the final 2xx response, and the UAC views that inclusion as a protocol violation. The UAC does so based on the fact that the SDP answer was reliably delivered to it in a 1xx response, and so it views additional SDP information as unnecessary in and ensuing reliable 1xx or 200 OK responses.

RFCs 3216 and 3262 do not specifically call out the UAS’s including SDP information in this way as a protocol violation. Still, the system allows you set enable the strip-dup-sdp option as a means of preventing the UAC from terminating sessions. With this option enabled, the Oracle® Enterprise Session Border Controller removes the SDP answer in subsequent reliable provisional or final 200 OK responses if it is identical to the SDP answer previously received.