B-35
Cisco SIP IP Phone Administrator Guide
Appendix B SIP Call Flows
Call Flow Scenarios for Successful Calls
Cisco SIP IP Phone-to-Cisco SIP IP Phone Network Call Forwarding
(Unconditional)
Figure B-10
illustrates successful call forwarding between Cisco SIP IP phones in which User B has
requested unconditional call forwarding from the network. When User A calls User B, the call is
immediately transferred to Cisco SIP IP phone C. In this call flow scenario, the end users are User A,
User B, and User C. They are all using Cisco SIP IP phones, which are connected via an IP network.
The call flow scenario is as follows:
1.
User B requests that the network forward all calls to Cisco SIP IP phone C.
2.
User A calls User B.
3.
The network transfers the call to Cisco SIP IP phone C.
Figure B-10 Cisco SIP IP Phone-to-Cisco SIP IP Phone Network Call Forwarding (Unconditional)
IP
IP
8. 200 OK
5. INVITE C
7. 200 OK
10. ACK
6. 180 Ringing
1. INVITE B
9. ACK
3. 302 Moved Temporarily
2. INVITE B
4. ACK
IP Network
SIP IP
Phone
User A
SIP IP
Phone
User B
SIP IP
Phone
User C
Proxy
Server
Redirect
Server
IP
41471
2-way RTP channel