Cisco Systems IP phone 7960 manual Gateway-to-Cisco SIP IP Phone-Called User Does Not Answer

Appendix B SIP Call Flows

Call Flow Scenarios for Failed Calls

Step	Action	Description
6	Disconnect (Busy)—Gateway 1	Gateway 1 sends a Disconnect message to PBX A.
	to PBX A
7	Release—PBX A to Gateway 1	PBX A sends a Release message to Gateway 1.
8	ACK—Gateway 1 to Cisco SIP	Gateway 1 sends a SIP ACK to the Cisco SIP IP phone. The
	IP phone	ACK confirms that User A has received the 486 Busy Here
		response. The call session attempt is now being terminated.
9	Release Complete—Gateway 1	Gateway 1 sends a Release Complete message to PBX A
	to PBX A	and the call session attempt is terminated.

Gateway-to-Cisco SIP IP Phone—Called User Does Not Answer

Figure B-14 illustrates the call flow in which User A initiates a call to User B but User B does not answer.

Figure B-14 Gateway-to-Cisco SIP IP Phone—Called User Does Not Answer

User A PBX A	GW1	IP Network	SIP IP Phone
			User B
			IP

1. Setup

3. Call Proceeding

6. Alerting

8.Disconnect

9.Release

11. Release Complete

2.INVITE

4.100 Trying

5.180 Ringing

7.CANCEL

10.200 OK

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	Cisco SIP IP Phone 7960 Administrator Guide
B-60	78-10497-02