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Cisco Unified IP Phone 7960G and 7940G Administration Guide for Release 8.0 (SIP)
OL-7890-01
Appendix B SIP Call Flows
Call Flow Scenarios for Successful Calls
Network Call Forwarding (No Answer)
Figure B-13
illustrates successful call forwarding between Cisco SIP IP phones in which User B has
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.
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.
2.
User A calls User B.
3.
User B does not answered.
4.
The network transfers the call to Phone C.
Figure B-13 Network Call Forwarding (No Answer)
IP
IP
13. 200 OK
7. 180 Ringing
5. INVITE B
9. 200 OK
12. 200 OK
11. 180 Ringing
15. ACK
10. INVITE C
8. CANCEL
6. 180 Ringing
1. INVITE B
14. ACK
3. 300 Multiple Choices
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
41473
2-way RTP channel