Yealink SIP-T4X Administrator's Manual page 451

Step
F27 BYE—User A to Proxy Server
F28 BYE—Proxy Server to User B
200OK—User B to Proxy
F29
Server
200OK—Proxy Server to User
F30
A
The following figure illustrates successful call forwarding between Yealink SIP IP phones
in which User B has enabled always call forward. The incoming call is immediately
forwarded to User C when User A calls User B. In this call flow scenario, the end users
are User A, User B, and User C. They are all using Yealink SIP IP phones, which are
connected via an IP network.
The call flow scenario is as follows:
1. User B enables always call forward, and the destination number is User C.
2. User A calls User B.
3. User B forwards the incoming call to User C.
Action
response indicates that User B accepts
the transfer.
User A terminates the call session by
sending a SIP BYE request to the proxy
server. The BYE request indicates that
User A wants to release the call.
The proxy server forwards the BYE
request to User B.
User B sends a SIP 200 OK response to
the proxy server. The 200 OK response
notifies User A that User B has received
the BYE request.
The proxy server forwards the SIP 200
OK response to User A.
Appendix
Description
435