Cisco SIP IP Phone User Manual

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Cisco SIP IP Phone Administrator Guide
AppendixB SIP Call Flows
Call Flow Scenarios for Successful Calls
Cisco SIP IP Phone-to Cisco SIP IP Phone Three-Way Calling
Figure B-12 illustrates successful three-way calling between Cisco SIP IP phones in which User B mixes
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 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 B puts User A on hold.
4. User B calls User C.
5. User C answers the call.
6. User B takes User A off hold.
13. ACK—Cisco SIP IP phone A to
SIP proxy server
Cisco SIP IP phone A sends a SIP ACK to the SIP proxy server. The ACK
confirms that Cisco SIP IP phone A has received the 200 OK response from
Cisco SIP IP phone C.
14. ACK—SIP proxy server to Cisco
SIP IP phone C
SIP proxy server forwards the SIP ACK to the Cisco SIP IP phone C. The ACK
confirms that Cisco SIP IP phone A has received the 200 OK response from
Cisco SIP IP phone C.
Step Action Description

Cisco SIP IP Phone Specifications

General

Brand	Cisco
Model	SIP IP Phone
Category	IP Phone
Language	English