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B-46
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
Figure B-17 Successful Call from a Cisco IP Phone to a Cisco IP Phone Using a SIP Emergency Proxy
Step
Action
Description
1.
INVITE—Cisco SIP IP phone
(A) to emergency proxy
The phone tries to connect to the emergency proxy by sending out the INVITE
message. The dial template for the emergency route is matched.
2.
100 Trying—Emergency proxy
to Cisco SIP IP phone (A)
The emergency proxy sends a SIP 100 Trying response to A. The response
indicates that the INVITE request has been received.
3.
INVITE—Emergency proxy to
Cisco SIP IP phone (B)
The backup proxy tries to connect to B by sending out the INVITE message.
4.
100 Trying—Cisco SIP IP phone
(B) to emergency proxy
User B sends a SIP 100 Trying response to the emergency proxy. The response
indicates that the INVITE request has been received.
5.
180 Ringing—Cisco SIP IP
phone (B) to emergency proxy
User B sends a SIP 180 Ringing response to the emergency proxy. The response
indicates that User B is being alerted.
6.
180 Ringing—Emergency proxy
to Cisco SIP IP phone (A)
The emergency proxy sends a SIP 180 Ringing response to User A. The response
indicates that the emergency proxy is being alerted.
7.
200 OK—Cisco SIP IP phone
(B) to emergency proxy
User B sends a SIP 200 OK response to the emergency proxy. The response
notifies the emergency proxy that the connection has been made.
8.
200 OK—Emergency proxy to
Cisco SIP IP phone (A)
The emergency proxy sends a SIP 200 OK response to User A. The response
notifies User A that the connection has been made.
IP
IP
SIP IP Phone
User A
SIP IP Phone
User B
Primary Proxy
Emergency Proxy
2. 100 Trying
3. INVITE
4. 100 Trying
5. 180 Ringing
6. 180 Ringing
7. 200 OK
8. 200 OK
9. ACK
10. ACK
11. BYE
12. BYE
13. 200 OK
14. 200 OK
2-way voice path
62071
1. INVITE (Matches dial template for emergency route)