If the incoming SIP request does not contain subscriber identification parameter, the routing system proceeds with the normal route resolution.
If an incoming SIP request has a subscriber identification parameter in the SIP request URI header, the call is for a SIP remote worker. The SIP routing system consults the internal SIP Registration in-memory database for determining the communication address of the SIP remote worker.
The subscriber identification parameter (subid_ipcs) is a unique number generated by Avaya SBC for each remote worker during the SIP registration process.
The following is a sample SIP Request line containing the subscriber identification parameter:
INVITE sip:5900021@10.1.222.20:5060;transport=tcp;avaya-sc-enabled;subid_ipcs=2803584614SIP/2.0(SIP Request Truncated)
If the SIP registration database lookup is successful, the SIP routing system uses the registration information for routing the call to the SIP remote worker.
The SIP routing system uses the following information available within the registration information to route the SIP call to the remote worker:
Remote worker Signaling IP Address / Port ( including NAT info)
Remote Signaling Transport (UDP/TCP/TLS)
Subscriber Flow that matched during the SIP Registration process
TCP/TLS connection information if connection-oriented transport is used by the remote worker.
The SIP routing system reuses the same TCP/TLS connection and Subscriber Flow for routing any SIP messages to the remote worker.
If the SIP registration database lookup fails, the call is rejected with a SIP 403 Forbidden error response and a Syslog/Incidence is raised. This event occurs when the SIP remote worker is no longer registered through the Avaya SBC.
