Yealink SIP-T2 SERIES Administrator's Manual page 1028

Administrator's Guide for SIP-T2 Series/T19(P) E2/T4 Series/CP860 IP Phones
Step
180 Ringing—Proxy Server to
F12
User A
200OK—User C to Proxy
F13
Server
200OK—Proxy Server to User
F14
A
F15 ACK— User A to Proxy Server
F16 ACK—Proxy Server to User C
The following figure illustrates successful call forwarding between Yealink SIP IP phones
in which User B has enabled no answer call forward. The incoming call is forwarded to
User C when User B does not answer the incoming call after a period of time. 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 no answer call forward, and the destination number is User C.
2. User A calls User B.
3. User B does not answer the incoming call.
4. User B forwards the incoming call to User C.
5. User C answers the call.
1006
Action
Ringing response indicates that the user
is being alerted.
The proxy server forwards the 180
Ringing response to User A. User A
hears the ring-back tone indicating that
User C is being alerted.
User C sends a SIP 200 OK response to
the proxy server. The 200 OK response
notifies User A that the connection has
been made.
The proxy server forwards the SIP 200
OK response to User A.
User A sends a SIP ACK to the proxy
server. The ACK confirms that User A
has received the 200 OK response. The
call session is now active.
The proxy server sends the ACK
message to User C.
Description