Phone Registration - Yealink SIP-T4X 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 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, sip:user@example.com. DNS mechanism is used such that the working server
is capable of resolving to multiple physical SIP servers for failover purpose. The working
server is deployed in redundant pairs, designated as primary and secondary servers.
The primary server is the highest priority server in a cluster of servers resolved by the
DNS server. The secondary server backs up a primary server when the primar y server
fails and offers the same functionality as the primary server.
Fallback Server: Server 2 is configured with the address of the fallback server. For
example, 192.168.1.15. A fallback server offers less functionality than the working server.

Phone Registration

Two registration methods for 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 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
Configuring Advanced Features
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