Matrix SPARSH VP710, User Manual

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Matrix SPARSH VP710 User Guide 595
At the start of a call, server availability is determined by SIP signaling failure. SIP signaling failure depends on the
SIP protocol being used as described below:
• If TCP is used, then the signaling fails if the connection or the send fails.
• If UDP is used, then the signaling fails if ICMP is detected or if the signal times out. If the signaling has
been attempted through all servers in the list (this list contains all the server addresses resolved by the
DNS server) and this is the last server, then the signaling fails after the complete UDP timeout defined in
RFC 3261. If it is not the last server in the list, the maximum number of retries depends on the configured
retry counts (configured by the parameter “account.X.sip_server.Y.retry_counts”).
Phone Registration
Registration method of the failover mode:
The IP phone must always register to the primary server first except in failover conditions. If this is unsuccessful,
the phone will re-register as many times as configured until the registration is successful. When the primary server
registration is unavailable, the secondary server will serve as the working server. As soon as the primary server
registration succeeds, it returns to be the working server.
Registration methods of the fallback mode include (not applicable to outbound proxy servers):
• Concurrent registration: The IP phone registers to SIP server 1 and SIP server 2 (working server and
fallback server) at the same time. Although the IP phone registers to two SIP servers, only one server
works at the same time. In the failure situation, a fallback server can take over the basic calling capability,
but without some advanced features (for example, shared lines and MWI) offered by the working server.By
default,
• Successive registration: The IP phone only registers to one server at a time. The IP phone first registers
to the working server. In the failure situation, the IP phone registers to the fallback server which can take
over all calling capabilities.
When registering to the working server, the IP phone must always register to the primary server first except in
failover conditions. When the primary server registration is unavailable, the secondary server will serve as the
working server.
Fallback Scenario
The following introduces a REGISTER fallback scenario. The SIP server 1 (working server) and SIP server 2
(fallback server) are configured with the IP address respectively for account 1. The parameter
“account.1.fallback.redundancy_type” is configured as 1 (Successive Registration).
REGISTER Fallback
The phone has ability to fail over to a fallback server when the working server has no response to a REGISTER
request.
• The phone sends a REGISTER request to the working server.
• The phone retries REGISTER requests to the working server (three times by default).