Yealink W60P Administrator's Manual page 348

Administrator's Guide for W60P DECT IP Phones
Phone Configuration for Redundancy Implementation
To assist in explaining the redundancy behavior, an illustrative example of how an DECT 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 with different IP addresses for failover purpose. The working server is
deployed in redundant pairs, designated as primary and secondary servers. The primary
server (e.g., 192.168.1.13) has the highest priority server in a cluster of servers resolved by
the DNS server. The secondary server (e.g., 192.168.1.14) 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.
Outgoing Call When the Working Server Connection Fails
When a user initiates a call, the DECT IP phone will go through the following steps to connect
the call:
Sends the INVITE request to the primary server.
1.
If the primary server does not respond correctly to the INVITE (that is,
2.
responds to the INVITE with 503 message or the request for responding with
message
times out
the secondary server.
If the secondary server is also unavailable, the DECT IP phone will try the fallback server
3.
until it either succeeds in making a call or exhausts all servers at which point the call will
fail.
At the start of a call, server availability is determined by SIP signaling failure. SIP signaling
328
(64*T1 seconds, defined in
the primary server
RFC 3261)), then tries to make the call using
100 Trying