Yealink SIP-T48G

Administrator’s Guide for SIP-T2 Series/T19(P) E2/T4 Series/CP860 IP Phones
874
Step
Action
Description
User C is being alerted.
F19
200OK—User C to Proxy
Server
User C sends a SIP 200 OK response to
the proxy server. The 200 OK response
notifies User A that the connection has
been made.
F20
200OK—Proxy Server to User
A
The proxy server forwards the SIP 200
OK response to User A. The 200 OK
response notifies User A that the
connection has been made.
F21
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.
F22
ACK—Proxy Server to User C
The proxy server sends the ACK
message to User C. The ACK confirms
that the proxy server has received the
200 OK response.