Yealink SIP-T38G, Administrator'S Manual

Page: 356 / 402

Appendix
343
Step Action Description
F7
200 OK— User B to Proxy
Server
User B sends a SIP 200 OK response to
the proxy server. The 200 OK response
notifies User A that the connection has
been made.
F8
200OK—Proxy Server to User
A
The proxy server forwards the 200 OK
message to User A. The 200 OK
response notifies User A that the
connection has been made.
F9 ACK—User A to Proxy Server
User A sends a SIP ACK to the proxy
server. The ACK confirms that User A
has received the 200 OK response. The
call session is now active.
F10 ACK—Proxy Server to User B
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.
F11 BYE—User B to Proxy Server
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.
F12 BYE—Proxy Server to User A
The proxy server forwards the SIP BYE
request to User A to notify that User B
wants to release the call.
F13
200 OK—User A to Proxy
Server
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.
F14
200 OK—Proxy Server to User
B
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.
The following figure illustrates the scenario of an unsuccessful call due to the reason of
the called user being busy. In this scenario, the two end users are User A and User B.
User A and User B are located at the Yealink SIP IP phones.