Yealink T46G Administrator's Manual page 408

Yealink Skype for Business HD IP Phones Administrator Guide
Step
F8 ACK—Proxy Server to User B
F9 REFER—User B to Proxy Server
202 Accepted—Proxy Server to
F10
User B
F11 REFER—Proxy Server to User A
202 Accepted—User A to Proxy
F12
Server
F13 BYE—User B to Proxy Server
F14 BYE—Proxy Server to User A
F15 200OK—User A to Proxy Server
F16 200OK—Proxy Server to User B
F17 INVITE—User A to Proxy Server
F18 INVITE—Proxy Server to User C
F19
180 Ringing—User C to Proxy
394
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 sends a REFER message to the proxy
server. User B performs a blind transfer of
User A to User C.
The proxy server sends a SIP 202 Accept
response to User B. The 202 Accepted
response notifies User B that the proxy
server has received the REFER message.
The proxy server forwards the REFER
message to User A.
User A sends a SIP 202 Accept response to
the proxy server. The 202 Accepted
response indicates that User A accepts the
transfer.
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 BYE request
to User A.
User A sends a SIP 200 OK response to the
proxy server. The 200 OK response confirms
that User A has received the BYE request.
The proxy server forwards the SIP 200 OK
response to User B.
User A sends a SIP INVITE request to the
proxy server. In the INVITE request, a
unique Call-ID is generated and the
Contact-URI field indicates that User A
requests the call.
The proxy server maps the SIP URI in the To
field to User C.
User C sends a SIP 180 Ringing response to
the proxy server. The 180 Ringing response
Description