Yealink SIP-T21 E2

Administrator’s Guide for SIP-T2 Series/T19(P) E2/T4 Series/T5 Series/CP860/CP920 IP Phones
1084
Step
Action
Description
proxy server. The 200 OK response
notifies User A that User B has received
the BYE request.
F30
200OK—Proxy Server to User A
The proxy server forwards the SIP 200 OK
response to User A.
Always Call Forward
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.
4. User C answers the call.
Call is established between User A and User C.
User A Proxy Server User B User C
F1. INVITE B
F2. INVITE B
F3. 302 Move Temporarily
F6. ACK
F7. INVITE C
F8. INVITE C
F9. 180 Ringing
F10. 180 Ringing
F11. 200 OK
F12. 200 OK
F13. ACK
F14. ACK
F4. ACK
2-way RTP channel established
F5. 302 Move Temporarily