Call From A Cisco Sip Ip Phone To A Cisco Sip Ip Phone Via A Backup Proxy - Cisco SIP IP Phone Administrator's Manual

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