D-1
Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator’s Guide (SIP)
OL-3410-01
APPENDIX
D

SIP Call Flows

This section describes some basic call flows for the Cisco ATA:
Supported SIP Request Methods, page D-1
Call Flow Scenarios for Successful Calls, page D-2
Note The term Cisco ATA refers to both the CiscoATA 186 and the Cisco ATA188, unless otherwise stated.

Supported SIP Request Methods

The Cisco ATA supports the following SIP request methods:
INVITE—Indicates 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.
REGISTER—Registers the address listed in the To header field with a SIP proxy.
NOTIFY—Notifies the user of the status of a transfer using REFER. Also used for remote reset.
OPTIONS
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
SIP 4xx—Client Failure responses
SIP 5xx—Server Failure responses
SIP 6xx—Global Failure responses