Yealink CP860 SERIES, Administrator'S Manual

Page: 1117 / 1126

Appendix
1091
Step Action Description

The port on which User B is prepared
to receive the RTP data is specified.
F2 INVITE—Proxy Server to User B
The proxy server maps the SIP URI in the
To field to User B. The proxy server sends
the INVITE message to User B.
F3
180 Ringing—User B to Proxy
Server
User B sends a SIP 180 Ringing response
to the proxy server. The 180 Ringing
response indicates that the user is being
alerted.
F4
180 Ringing—Proxy Server to
User A
The proxy server forwards the 180 Ringing
response to User A. User A hears the ring-
back tone indicating that User B is being
alerted.
F5
302 Move Temporarily—User B
to Proxy Server
User B sends a SIP 302 Moved
Temporarily message to the proxy server.
The message indicates that User B is not
available at SIP phone B. User B rewrites
the contact-URI.
F6 ACK—Proxy Server to User B
The proxy server sends a SIP ACK to User
B, the ACK message notifies User B that
the proxy server has received the ACK
message.
F7
302 Move Temporarily—Proxy
Server to User A The proxy server forwards the 302 Moved
Temporarily message to User A.
F8 ACK—User A to Proxy Server
User A sends a SIP ACK to the proxy
server. The ACK message notifies the
proxy server that User A has received the
ACK message.
F9 INVITE—User A to Proxy Server
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.
F10 INVITE—Proxy Server to User C
The proxy server forwards the SIP INVITE
request to User C.
F11
180 Ringing—User C to Proxy
Server
User C sends a SIP 180 Ringing response
to the proxy server. The 180 Ringing
response indicates that the user is being