B-1
Cisco SIP IP Phone Administrator Guide
A P P E N D I X
B
SIP Call Flows
This chapter includes the following sections:
•
Call Flow Scenarios for Successful Calls, page B-1
•
Call Flow Scenarios for Failed Calls, page B-46
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 callee.
•
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 reset.
The following types of responses are used by SIP and generated by the Cisco SIP gateway:
•
SIP 1xx—Informational Responses
•
SIP 2xx—Successful Responses
•
SIP 3xx—Redirection Responses
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SIP 4xx—Client Failure Responses
•
SIP 5xx—Server Failure Responses
•
SIP 6xx—Global Failure Responses
Call Flow Scenarios for Successful Calls
This section describes call flows for the following scenarios, which illustrate successful calls:
•
Gateway-to Cisco SIP IP Phone—Successful Call Setup and Disconnect, page B-2
•
Gateway-to-Cisco SIP IP Phone—Successful Call Setup and Call Hold, page B-4
•
Cisco SIP IP Phone-to-Cisco SIP IP Phone Simple Call Hold, page B-6
