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B-1
Cisco Unified IP Phone 7960G and 7940G Administration Guide for Release 8.0 (SIP)
OL-7890-01
A P P E N D I X
B
SIP Call Flows
This appendix includes the following sections:
•
Call Flow Scenarios for Successful Calls, page B-2
•
Call Flow Scenarios for Failed Calls, page B-47
SIP uses the following request methods:
•
INVITE—Indicates that a user or service is being invited to participate in a call session.
•
ACK—Confirms that the client has received a final response to an INVITE request.
•
BYE—Terminates a call and can be sent by either the caller or the called party.
•
CANCEL—Cancels any pending searches but does not terminate a call that has already been
accepted.
•
OPTIONS—Queries the capabilities of servers.
•
REGISTER—Registers the address listed in the To header field with a SIP server.
•
REFER—Indicates that the user (recipient) should contact a third party for use in transferring
parties.
•
NOTIFY—Notifies the user of the status of a transfer using REFER. Also used for remote reboot
and message waiting indication (MWI).
The following types of responses are used by SIP and generated by the Cisco SIP gateway:
•
SIP 1
xx
—Informational Responses
•
SIP 2
xx
—Successful Responses
•
SIP 3
xx
—Redirection Responses
•
SIP 4
xx
—Client Failure Responses
•
SIP 5
xx
—Server Failure Responses
•
SIP 6
xx
—Global Failure Responses
Note
If you have enabled the rfc_2543_hold parameter, the phone will use the RFC 2543 method for putting
a call on hold, and will set the media address to 0.0.0.0. The examples in this chapter assume that this
parameter is not enabled, and show the phone using the RFC 3264 method.
For example, if the rfc_2543_hold parameter is enabled, the INVITE request in step 5 in the
“Simple
Call Hold” section on page B-9
would be sent as INVITE (c=IN IP4 0.0.0.0 a=inactive).