Network Call Forwarding (No Answer - Cisco 7960G Administrator's Manual

Call Flow Scenarios for Successful Calls

Network Call Forwarding (No Answer)

Figure B-13
requested call forwarding from the network in the event that there is no answer. When User A calls
User B, the proxy server tries to place the call to Phone B, and, if there is no answer, the call is
transferred to 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.
2.
3.
4.
Figure B-13 Network Call Forwarding (No Answer)
SIP IP
Phone
User A
Cisco SIP IP Phone Administrator Guide, Release 6.x and 7.x
B-36
illustrates successful call forwarding between Cisco SIP IP phones in which User B has
User B requests that if the phone (Phone B) is not answered within a set amount of time, the network
should forward incoming calls to Phone C.
User A calls User B.
User B does not answered.
The network transfers the call to Phone C.
IP
Proxy
Server
1. INVITE B
7. 180 Ringing
13. 200 OK
14. ACK
2-way RTP channel
IP Network
Redirect
Server
2. INVITE B
3. 300 Multiple Choices
4. ACK
5. INVITE B
6. 180 Ringing
8. CANCEL
9. 200 OK
10. INVITE C
11. 180 Ringing
12. 200 OK
15. ACK
Appendix B SIP Call Flows
IP IP
SIP IP SIP IP
Phone Phone
User B User C