Matrix Sparsh VP110 User Manual page 266

• Phone A places a call to Phone B.
• Phone B answers the call.
The following SIP messages appear:
• Phone A sends an INVITE request to the working server.
• Phone A retries INVITE requests to the working server (three times by default).
• After no response from the working server, the phone sends an INVITE request to the fallback server.
• The fallback server responds with 200 OK to the INVITE request.
Phone A sends REGISTER requests to the working server to detect whether the server is available. When the
working server recovers, the phone has ability to fail back the INVITE request to the working server.
Failover Scenario
The following introduces a REGISTER failover scenario. The SIP server 1 is configured with the domain name of
the working server for account 1. The working server is resolved to two SIP servers (primary server and secondary
server) using the DNS mechanism. The parameter "account.1.sip_server.1.failback_mode" is configured as 0
(newRequests) and "account.1.sip_server.1.register_on_enable" is configured as 0 (Disabled).
REGISTER Failover
The phone has ability to fail over to a secondary server when the primary server has no response to a REGISTER
request.
• The phone sends REGISTER request to the primary server.
• The phone retries REGISTER requests to the primary server (three times by default).
• After no response from the primary server, the phone sends a REGISTER request to the secondary server.
• The secondary server responds with 200 OK to the REGISTER request.
The phone waits until next REGISTER attempt and then sends next REGISTER request to the primary server.
When the primary server recovers, the phone has ability to fail back next REGISTER request to the primary server.
INVITE Failover
The phone has ability to fail over to a secondary server when there is no response to an INVITE request.
• Phone A places a call to Phone B.
• Phone B answers the call.
The following SIP messages appear:
• Phone A sends an INVITE request to the primary server.
• Phone A retries INVITE requests to the primary server (three times by default).
• After no response from the primary server, the phone sends an INVITE request to the secondary
server.
258 Matrix SPARSH VP110 User Guide