Cisco 7960G Administrator's Manual page 101
Sip
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Also See for 7960G:
- Administration manual (184 pages) ,
- User manual (122 pages) ,
- Phone manual (74 pages)
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Appendix B
SIP Call Flows
Step
Action
Setup—PBX A to Gateway 1
1.
INVITE—Gateway 1 to Cisco SIP IP phone
2.
Call Proceeding—Gateway 1 to PBX A
3.
100 Trying—Cisco IP 7960G/7940G phone
4.
to Gateway 1
5.
180 Ringing—Cisco SIP IP phone to
Gateway 1
6.
Alerting—Gateway 1 to the PBX A
200 OK—Cisco SIP IP phone to Gateway 1
7.
Connect—Gateway 1 to PBX A
8.
ACK—Gateway 1 to Cisco SIP IP phone
9.
Connect ACK—PBX A to Gateway 1
10.
11.
INVITE—Cisco SIP IP phone to Gateway 1
12.
200 OK—Gateway 1 to Cisco SIP IP phone
13.
ACK—Cisco SIP IP phone to Gateway 1
Description
Call setup is initiated between PBX A and Gateway 1. Setup includes
the standard transactions that take place as User A attempts to call
User B.
Gateway 1 maps the SIP URL phone number to a dial peer. The dial
peer includes the IP address and the port number of the SIP-enabled
entity to contact. Gateway 1 sends a SIP INVITE request to the
address it receives as the dial peer, which, in this scenario, is the IP
phone. In the INVITE request:
The IP address of the phone is inserted in the Request-URI field.
•
PBX A is identified as the call session initiator in the From field.
•
A unique numeric identifier is assigned to the call and is inserted
•
in the Call-ID field.
The transaction number within a single call leg is identified in
•
the CSeq field.
The media capability that User A is ready to receive is specified.
•
The port on which the gateway is prepared to receive the RTP
•
data is specified.
Gateway 1 sends a Call Proceeding message to the PBX A to
acknowledge the Call Setup request.
The phone sends a SIP 100 Trying response to Gateway 1. The
response indicates that the INVITE request has been received.
The phone sends a SIP 180 Ringing response to Gateway 1. The
response indicates that the user is being alerted.
Gateway 1 sends an Alert message to User A. The message indicates
that Gateway 1 has received a 180 Ringing response from the phone.
User A hears the ringback tone that indicates that User B is being
alerted.
The phone sends a SIP 200 OK response to Gateway 1. The response
notifies Gateway 1 that the connection has been made.
Gateway 1 sends a Connect message to PBX A. The message notifies
PBX A that the connection has been made.
Gateway 1 sends a SIP ACK to the phone. The ACK confirms that
User A has received the 200 OK response. The call session is now
active.
PBX A acknowledges Gateway 1's Connect message.
User B puts User A on hold. The phone sends a SIP INVITE request
to Gateway 1.
Gateway 1 sends a SIP 200 OK response to the phone. The response
notifies the phone that the INVITE was successfully processed.
The phone sends a SIP ACK to Gateway 1. The ACK confirms that
the phone has received the 200 OK response. The call session is now
temporarily inactive. No RTP packets are being sent.
Cisco SIP IP Phone Administrator Guide, Release 6.x and 7.x
Call Flow Scenarios for Successful Calls
B-5
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