Cisco Systems IP phone 7960 manual Cisco SIP IP Phone 7960 Administrator Guide

Appendix B SIP Call Flows

Call Flow Scenarios for Successful Calls

Step	Action	Description
14	BYE—Cisco SIP IP phone B to	The call continues and then User B hangs up. Cisco SIP IP
	Cisco SIP IP phone A	phone B sends a SIP BYE request to Cisco SIP IP phone A.
		The SIP BYE request includes the Also header. The Also
		header indicates that User C needs to be brought into the
		call while User B hangs up. The header distinguishes the
		call transfer BYE request from a normal disconnect BYE
		disconnect BYE request.
15	200 OK—Cisco SIP IP phone A	Cisco SIP IP phone A sends a SIP 200 OK message to
	to Cisco SIP IP phone B	Cisco SIP IP phone B. The 200 OK response notifies Cisco
		SIP IP phone B that the BYE request has been received.
		The call session between User A and User B is now
		terminated.
The RTP channel between Cisco SIP IP phone A and Cisco SIP IP phone B is torn down.
16	INVITE—Cisco SIP IP phone A	At the request of Cisco SIP IP phone B, Cisco SIP IP phone
	to Cisco SIP IP phone C	A sends a SIP INVITE request to Cisco SIP IP phone C.
	(Requested by Cisco SIP IP	The INVITE request is an invitation to User C to
	phone B)	participate in a call session.
17	180 Ringing—Cisco SIP IP	Cisco SIP IP phone C sends a SIP 180 Ringing response to
	phone C to Cisco SIP IP phone A	Cisco SIP IP phone A.
18	200 OK—Cisco SIP IP phone C	Cisco SIP IP phone C sends a SIP 200 OK response to
	to Cisco SIP IP phone A	Cisco SIP IP phone A. The 200 OK response notifies Cisco
		SIP IP phone A that the connection has been made.
19	ACK—Cisco SIP IP phone A to	Cisco SIP IP phone A sends a SIP ACK to Cisco SIP IP
	Cisco SIP IP phone C	phone C. The ACK confirms that Cisco SIP IP phone A has
		received the 200 OK response from Cisco SIP IP phone C.

A two-way RTP channel is established between Cisco SIP IP phone A and Cisco SIP IP phone C.

	Cisco SIP IP Phone 7960 Administrator Guide
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