Yealink SIP-T54S Administrator's Manual page 472

Administrator's Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series/CP860/CP920 IP Phones
incoming INVITE message by responding with a 302 Moved Temporarily message, which
contains a Contact header with a new URI that should be tried. Three types of call forward:
Always Forward -- Forward the incoming call immediately.

Busy Forward -- Forward the incoming call when the IP phone or the specified account is

busy.
No Answer Forward -- Forward the incoming call after a period of ring time.

Call forward can be configured on a phone or a per-line basis depending on the call forward
mode. The following describes the call forward modes:
Phone (default): Call forward feature is effective for the IP phone.

Custom: Call forward feature can be configured for each or all accounts.

The call forward feature is enabled by default, and you have the option of disabling it (not
applicable to CP860 IP phones). Users have no permission to configure call forward on the
phone if call forward feature is disabled. The server-side call forward settings deactivate the
local call forward settings. If the server-side call forward feature is activated on any of the IP
phone's registrations, the other registrations are not affected. DND activated on the IP phone
deactivates the local no answer forward settings.
The call forward on code and call forward off code configured on IP phones are used to
activate/deactivate the server-side call forward feature. They may vary on different servers.
Diversion/History-Info
IP phones support the redirected call information sent by the SIP server with Diversion header,
per draft-levy-sip-diversion-08, or History-info header, per
info header is used to inform the IP phone of a call's history. For example, when a phone has
been set to enable call forward, the Diversion/History-info header allows the receiving phone to
indicate who the call was from, and from which phone number it was forwarded.
Forward International
Forward international allows users to forward an incoming call to an international telephone
number (the prefix is 00). This feature is enabled by default.
Forward Emergency
Forward emergency allows the incoming calls from some authorized numbers not to be
forwarded when the call forward feature is enabled. The incoming call will not be logged in the
Forwarded Calls list. This feature is disabled by default.
446
RFC 4244. The Diversion/History-