Three-Way Calling - Cisco 7960G Administrator's Manual

Call Flow Scenarios for Successful Calls
Step Action
14. ACK—Phone A to SIP proxy
server
15. ACK—SIP proxy server to
Phone C

Three-Way Calling

Figure B-14
two RTP channels and therefore establishes a conference bridge between User A and User C. In this call
flow scenario, the end users are User A, User B, and User C. They are all using Cisco IP 7960G/7940G
phones, which are connected using an IP network.
The call flow scenario is as follows:
1.
2.
3.
4.
5.
6.
Cisco SIP IP Phone Administrator Guide, Release 6.x and 7.x
B-38
Description
Phone A sends a SIP ACK to the SIP proxy server. The ACK confirms that
Phone A has received the 200 OK response from Phone C.
The SIP proxy server forwards the SIP ACK to the Phone C. The ACK confirms
that Phone A has received the 200 OK response from Phone C.
illustrates successful three-way calling between Cisco SIP IP phones in which User B mixes
User A calls User B.
User B answers the call.
User B puts User A on hold.
User B calls User C.
User C answers the call.
User B takes User A off hold.
Appendix B SIP Call Flows