B-47
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 Failed Calls
Call Flow Scenarios for Failed Calls
This section describes call flows for the following scenarios, which illustrate unsuccessful calls:
•
Gateway to Cisco SIP IP Phone in a SIP Network, page B-47
•
Cisco SIP IP Phone to Cisco SIP IP Phone in a SIP Network, page B-52
Gateway to Cisco SIP IP Phone in a SIP Network
The following scenarios are failed calls in the gateway to a Cisco SIP IP phone:
•
Called Number Is Busy, page B-47
•
Called Number Does Not Answer, page B-49
•
Client, Server, or Global Error, page B-50
Called Number Is Busy
Figure B-18
illustrates an unsuccessful call in which Use A initiates a call to User B, but User B is on
the phone and is unable or unwilling to take another call.
9.
ACK—Cisco SIP IP phone
(A) to emergency proxy
A acknowledges the emergency proxy’s Connect message.
10.
ACK—Emergency proxy to
Cisco SIP IP phone (B)
The emergency proxy acknowledges B’s Connect message.
11.
BYE—Cisco SIP IP phone
(A) to emergency proxy
A terminates the call session and sends a SIP BYE request to the emergency
proxy. The request indicates that A wants to release the call.
12.
BYE—Emergency proxy to
Cisco SIP IP phone (B)
The emergency proxy terminates the call session and sends a SIP BYE request to
User B. The request indicates that the emergency proxy wants to release the call.
13.
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 B has received the BYE request.
14.
200 OK—Emergency proxy to
Cisco SIP IP phone (A)
The emergency proxy sends a SIP 200 OK response to A. The response notifies A
that the emergency proxy has received the BYE request.
Step
Action
Description