1/5/2007
EAG Gateway Series Administration Guidelines
MAG-06007 Rev. A
Call Agent provides instructions to the endpoints to check for any events and - if there is any - create
signals. The endpoints are designed in such a way as to automatically communicate changes in
service state to the Call Agent. The Call Agent can audit endpoints and the connections on endpoints.
401/402 Response Code
Response Code is a 3-digit response to the request, indicating the processing results for requests. For
example, 401 and 402 represent responses to the on-hook and off-hook operations.
NTFY
Notification, or Notify, a command sent from gateway to call agent.
SIP (Session Initiation Protocol)
Session Initiation Protocol (SIP) is the Internet Engineering Task Force's (IETF's) standard for
multimedia conferencing over IP. SIP is an ASCII-based, application-layer control protocol (defined in
RFC 2543) that can be used to establish, maintain, and terminate calls between two or more end
points.
Like other VoIP protocols, SIP is designed to address the functions of signaling and session
management within a packet telephony network. Signaling allows call information to be carried across
network boundaries. Session management provides the ability to control the attributes of an
end-to-end call.
SIP provides the capabilities to:
․
Determine the location of the target end point—SIP supports address resolution, name mapping,
and call redirection.
․
Determine the media capabilities of the target end point—Via Session Description Protocol
(SDP), SIP determines the "lowest level" of common services between the end points.
Conferences are established using only the media capabilities that can be supported by all end
points.
․
Determine the availability of the target end point—If a call cannot be completed because the
target end point is unavailable, SIP determines whether the called party is already on the phone
or did not answer in the allotted number of rings. It then returns a message indicating why the
target end point was unavailable.
․
Establish a session between the originating and target end point—If the call can be completed,
SIP establishes a session between the end points. SIP also supports mid-call changes, such as
the addition of another end point to the conference or the changing of a media characteristic or
codec.
․
Handle the transfer and termination of calls—SIP supports the transfer of calls from one end
point to another. During a call transfer, SIP simply establishes a session between the transferee
and a new end point (specified by the transferring party) and terminates the session between the
transferee and the transferring party. At the end of a call, SIP terminates the sessions between
all parties.
Conferences can consist of two or more users and can be established using multicast or multiple
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