Cisco SIP IP Phone User Manual

B-55
Cisco SIP IP Phone Administrator Guide
Appendix B SIP Call Flows
Call Flow Scenarios for Failed Calls
Figure B-20 A Successful Call from a Cisco SIP IP Phone to a Gateway (Backup Proxy)
Step Action Description
1. INVITE—Cisco SIP IP phone to
primary proxy
Cisco SIP IP phone tries to connect to the proxy by sending out the INVITE
message.
2. INVITE—Cisco SIP IP phone to
primary proxy (second try)
Cisco SIP IP phone retries a second time to connect to the proxy by sending out
the INVITE message.
3. INVITE—Cisco SIP IP phone to
primary proxy (third try)
Cisco SIP IP phone retries a third time to connect to the proxy by sending out the
INVITE message.
4. INVITE—Cisco SIP IP phone to
primary proxy (fourth try)
Cisco SIP IP phone retries a fourth time to connect to the proxy by sending out
the INVITE message.
IP
SIP IP Phone
User A
Primary
1. INVITE
2. INVITE (retry)
3. INVITE (retry)
4. INVITE (retry)
5. INVITE (retry)
6. INVITE (retry)
7. INVITE (retry)
8. INVITE (retry)
9. Setup
10. Call Proceeding
11. 100 Trying
12. Alerting
13. 180 Ringing
14. Connect
15. 200 OK
16. ACK
17. Connect ACK
18. BYE
2-way voice path
19. Disconnect
20. Release
22. Release Complete
21. 200 OK
GW PBX
User B
62069

Cisco SIP IP Phone Specifications

General

Brand	Cisco
Model	SIP IP Phone
Category	IP Phone
Language	English