Yealink CD860, Administrator'S Manual

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Administrator’s Guide for SIP-T2 Series/T19(P) E2/T4 Series/CP860 IP Phones
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fallback purpose.
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