Cisco SIP IP Phone User Manual

B-57
Cisco SIP IP Phone Administrator Guide
Appendix B SIP Call Flows
Call Flow Scenarios for Failed Calls
Figure B-21 A Successful Call from a Cisco SIP IP Phone to a Cisco SIP IP Phone via a Backup Proxy
Step Action Description
1. INVITE—Cisco SIP IP Phone
(User A) to primary proxy
Cisco SIP IP Phone tries to connect to the primary proxy by sending out the
INVITE message.
2. INVITE—Cisco SIP IP phone
(User A) to primary proxy
(second try)
Cisco SIP IP phone retries a second time to connect to the primary proxy by
sending out the INVITE message.
3. INVITE—Cisco SIP IP phone
(User A) to primary proxy (third
try)
Cisco SIP IP phone retries a third time to connect to the primary proxy by
sending out the INVITE message.
IP IP
SIP IP Phone
User A
1. INVITE
2. INVITE (retry)
3. INVITE (retry)
4. INVITE (retry)
5. INVITE (retry)
6. INVITE (retry)
7. INVITE (retry)
8. INVITE (retry)
9. 100 Trying
10. INVITE
11. 100 Trying
12. 180 Ringing
13. 180 Ringing
14. 200 OK
15. 200 OK
16. ACK
17. ACK
18. BYE
2-way voice path
19. BYE
20. 200 OK
21. 200 OK
Primary Proxy Backup Proxy
SIP IP Phone
User B
62068

Cisco SIP IP Phone Specifications

General

Brand	Cisco
Model	SIP IP Phone
Category	IP Phone
Language	English