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

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 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 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 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.
Registration methods of the fallback mode include:
Concurrent registration (default): 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 advanced features (for example, shared
lines, call recording and MWI) offered by the working server. It is not applicable to
outbound proxy servers
Configuring Advanced Features
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