Unsuccessful Call Setup-Called User Is Busy - Yealink CP969 Administrator's Manual

Step
F10 ACK—Proxy Server to User B
F11 BYE—User B to Proxy Server
F12 BYE—Proxy Server to User A
F13 200 OK—User A to Proxy Server
F14 200 OK—Proxy Server to User B
Unsuccessful Call Setup—Called User is Busy
The following figure illustrates the scenario of an unsuccessful call caused by the called user's
being busy. In this scenario, the two end users are User A and User B. User A and User B are
located at Yealink SIP IP phones.
The call flow scenario is as follows:
User A calls User B.
1.
User B is busy on the IP phone and unable or unwilling to take another call.
2.
Action
now active.
The proxy server sends the SIP ACK to User
B. The ACK confirms that the proxy server
has received the 200 OK response. The call
session is now active.
User B terminates the call session by
sending a SIP BYE request to the proxy
server. The BYE request indicates that User
B wants to release the call.
The proxy server forwards the SIP BYE
request to User A to notify that User B
wants to release the call.
User A sends a SIP 200 OK response to the
proxy server. The 200 OK response
indicates that User A has received the BYE
request. The call session is now terminated.
The proxy server forwards the SIP 200 OK
response to User B to indicate that User A
has received the BYE request. The call
session is now terminated.
Appendix
Description
809