Gateway-To-Cisco Sip Ip Phone-Called User Does Not Answer - Cisco 7960 Administrator's Manual

Call Flow Scenarios for Failed Calls
Step Action
6
Disconnect (Busy)—Gateway 1
to PBX A
7 Release—PBX A to Gateway 1
8
ACK—Gateway 1 to Cisco SIP
IP phone
9
Release Complete—Gateway 1
to PBX A
Gateway-to-Cisco SIP IP Phone—Called User Does Not Answer
Figure B-14 illustrates the call flow in which User A initiates a call to User B but
User B does not answer.
Figure B-14 Gateway-to-Cisco SIP IP Phone—Called User Does Not Answer
PBX A
User A
1. Setup
3. Call Proceeding
6. Alerting
8. Disconnect
9. Release
11. Release Complete
Cisco SIP IP Phone 7960 Administrator Guide
B-60
Description
Gateway 1 sends a Disconnect message to PBX A.
PBX A sends a Release message to Gateway 1.
Gateway 1 sends a SIP ACK to the Cisco SIP IP phone. The
ACK confirms that User A has received the 486 Busy Here
response. The call session attempt is now being terminated.
Gateway 1 sends a Release Complete message to PBX A
and the call session attempt is terminated.
GW1 IP Network
2. INVITE
4. 100 Trying
5. 180 Ringing
7. CANCEL
10. 200 OK
Appendix B SIP Call Flows
SIP IP Phone
User B
IP
78-10497-02