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Cisco SIP IP Phone 7960 Administrator Guide
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AppendixB SIP Call Flows Call Flow Scenarios for Failed Calls
Gateway-to-Cisco SIP IP Phone—Client, Server, or Global Error

Figure B-15 illustrates an unsuccessful call in which User A initiates a call to

User B and receives a class 4xx, 5xx, or 6xx response.

FigureB-15 Gateway-to-Cisco SIP IP Phone—Client, Server, or Global Error

IP
SIP IP Phone
User B
3. Call Proceeding
6. Disconnect
1. Setup
PBX A
User A GW1 IP Network
4. 100 Trying
5. 4xx/5xx/6xx Failure
8. ACK
2. INVITE
9. Release Complete
7. Release
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