Yealink SIP-T2 Series User Manual

Appendix
1023
Step
Action
Description
F13
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.
F14
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.
F15
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.
F16
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.
The following figure illustrates successful 3-way calling between Yealink IP phones in which User
A mixes two RTP channels and therefore establishes a conference between User B and User C. In
this call flow scenario, the end users are User A, User B, and User C. They are all using Yealink SIP
IP phones, which are connected via an IP network.
The call flow scenario is as follows:
1. User A calls User B.
2. User B answers the call.
3. User A places User B on hold.
4. User A calls User C.
5. User C answers the call.

Yealink SIP-T2 Series Specifications

General

Brand	Yealink
Model	SIP-T2 Series
Category	IP Phone
Language	English