Yealink SIP-T2XP, Руководство администратора

Страница: 563 / 589

Appendix
545
Step Action Description
F14
INVITE—Proxy Server to User
B The proxy server forwards the mid-call
INVITE message to User B.
F15
200 OK—User B to Proxy
Server
User B sends a 200 OK to the proxy
server. The 200 OK response indicates
that the INVITE was successfully
processed.
F16
200 OK—Proxy Server to User
A
The proxy server forwards the 200 OK
response to User A. The 200 OK
response notifies User B is successfully
placed on hold.
F17 ACK—User A to Proxy Server
User A sends an ACK message to the
proxy server. The ACK confirms that
User A has received the 200 OK
response. The call session is now
temporarily inactive. No RTP packets
are being sent.
F18 ACK—Proxy Server to User B
The proxy server sends the ACK
message to User B. The ACK confirms
that the proxy server has received the
200 OK response.
F19
200 OK—User A to Proxy
Server
User A sends a 200 OK response to the
proxy server. The 200 OK response
notifies that the connection has been
made.
F20 200 OK—Proxy Server User C
The proxy server forwards the 200 OK
message to User C.
F21 ACK—User C to Proxy Server
User C sends a SIP ACK to the proxy
server. The ACK confirms that User C
has received the 200 OK response. The
call session is now active.
F22 ACK—Proxy Server to User A
The proxy server forwards the SIP ACK
to User A to confirm that User C has
received the 200 OK response.
The following figure illustrates a successful call between Yealink SIP IP phones in which
two parties are in a call and then one of the parties transfers the call to a third party
without consultation. This is called a blind transfer. In this call flow scenario, the end