Phone Registration - Yealink SIP-T2 Series Administrator's Manual

Administrator's Guide for SIP-T23 & T23P & T23G IP Phones
Phone Configuration for Redundancy Implementation
To assist in explaining the redundancy behavior, an illustrative example of how an IP
phone may be configured is shown as below. In the example, server redundancy for
fallback and failover purposes is deployed. Two separate SIP servers (a working server
and a fallback server) are configured for per line registration.
Working Server: Server 1 is configured with the domain name of the working server. For
example, yealink.pbx.com. DNS mechanism is used such that the working server is
resolved to multiple SIP servers for failover purpose. The working server is deployed in
redundant pairs, designated as primary and secondary servers. The primary server has
the highest priority server in a cluster of servers resolved by the DNS server. The
secondary server backs up a primary server when the primary server fails and offers
the same functionality as the primary server.
Fallback Server: Server 2 is configured with the IP address of the fallback server. For
example, 192.168.1.15. A fallback server offers less functionality than the working server.

Phone Registration

Registration methods of the fallback mode:
Concurrent registration: The IP phone registers to two SIP servers (working server

and fallback server) at the same time. In a failure situation, a fallback server can
take over the basic calling capability, but without some of the advanced features
offered by the working server (default registration method).
Successive registration: The IP phone only registers to one server at a time. The IP

phone first registers to the working server. In a failure situation, the IP phone
registers to the fallback server.
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
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