SIP Registration Local Expiration
When you deploy multiple Oracle® Enterprise Session Border Controllers (E-SBC) in series and they have registration caching and HNT configured, registration cache entries might expire prematurely in instances with several devices provisioned with the same address of record (AoR). Now you can configure a SIP interface option to prevent the premature expiration.
When you use registration caching and HNT, the E-SBC adjusts the expiration time it sends to user agents (UAs) in REGISTER responses based on the registration interval you configure. It can be the case that a SIP user has multiple registered contact endpoints at the UA to which a response is sent. If the URI in the Contact contains the UA‘s address and that UA included the Contact in the REGISTER request, then the Contact is seen as exclusively belonging to that UA. In the REGISTER response, this Contact (exclusive to the UA) includes the local expiration time, a time based on the SIP interface configuration’s registration or NAT interval value. Additional Contacts (not exclusive to the UA) in the REGISTER response have the expiration time from the REGISTER response the registrar sent to the E-SBC.
It is this default behavior can cause registration cache entries to expire prematurely in the E-SBC nearest a registrar when multiple E-SBCs are deployed in series. Multiple registering UAs for a single SIP user, for example, might trigger the early expiration. The SIP you can configure an option per SIP interface that causes the E-SBC to send the local registration expiration time in all in the Expires parameter of all Contact headers included in REGISTER responses sent from the SIP interface.
