Cisco Sip Ip Phone To Cisco Sip Ip Phone; Simple Call Hold - Cisco 7960G Administrator's Manual

Appendix B SIP Call Flows
Step Action
INVITE—Cisco SIP IP phone to
1.
the gateway (emergency proxy)
Setup—Gateway to the PBX
2.
Call Proceeding—PBX to the
3.
gateway
100 Trying—Gateway to Cisco
4.
SIP IP phone (User A)
Alerting—PBX to the gateway
5.
180 Ringing—Gateway to Cisco
6.
SIP IP phone (User A)
7. Connect—PBX to the gateway
200 OK—Gateway to Cisco SIP
8.
IP phone (User A)
9. ACK—Cisco SIP IP phone
(User A) to the gateway
10. Connect ACK—Gateway to the
PBX
BYE—Cisco SIP IP phone
11.
(User A) to the gateway
Disconnect—Gateway to the
12.
PBX
Release—PBX to the gateway
13.
200 OK—Gateway to Cisco SIP
14.
IP phone (User A)
Release Complete—Gateway to
15.
the PBX

Cisco SIP IP Phone to Cisco SIP IP Phone

The following sections describe and illustrate successful calls from a Cisco SIP IP phone to another
Cisco SIP IP phone:
•
•
•
•
•
•
•
Description
The phone tries to connect to the gateway (emergency proxy) by sending out the
INVITE message. The dial template for the emergency route is matched.
Call setup is initiated between the gateway and the PBX. Setup includes the
standard transactions that take place as User A attempts to call User B.
The PBX sends a Call Proceeding message to the gateway to acknowledge the Call
Setup request.
The gateway sends a SIP 100 Trying response to User A. The response indicates
that the INVITE request has been received.
The PBX sends an Alert message to the gateway. The message indicates that the
PBX has received a 100 Trying Ringing response from the gateway.
The gateway sends a SIP 180 Ringing response to User A. The response indicates
that the gateway is being alerted.
The PBX sends a Connect message to the gateway. The message notifies the
gateway that the connection has been made.
The gateway sends a SIP 200 OK response to User A. The response notifies
User A that the connection has been made.
User A sends a SIP ACK to the gateway. The ACK confirms that User A has
received the 200 OK response. The call session is now active.
The gateway acknowledges PBX's Connect message.
User A terminates the call session and sends a SIP BYE request to the gateway.
The request indicates that User A wants to release the call.
The gateway sends a Disconnect message to the PBX.
The PBX sends a Release message to the gateway.
The gateway sends a SIP 200 OK response to User A. The response notifies
User A that the gateway has received the BYE request.
The gateway sends a Release Complete message to the PBX and the call session
terminates.
Simple Call Hold, page B-8
Call Hold with Consultation, page B-10
Call Waiting, page B-13
Call Transfer Without Consultation, page B-17
Call Transfer Without Consultation Using Failover, page B-20
Call Transfer with Consultation, page B-23
Call Transfer with Consultation Using Failover, page B-27
Call Flow Scenarios for Successful Calls
Cisco SIP IP Phone Administrator Guide, Release 6.x and 7.x
B-7