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MultiVOIP User Guide Embedded Gatekeeper
485
Summary of
H.323 RAS* Messages (Registration, Admission, & Status)
of the H.225 Call Signaling Protocol
In a gatekeeper-controlled H.323 network, when call is made, the RAS
channel between gatekeeper and endpoint is the first logical channel
opened.
Admission Control
Messages
With an ARQ, an endpoint asks to participate
in a phone call. The gatekeeper can either
grant the request (by sending an ACF
message )
or deny the request
(by sending an ARJ message). When
admission is granted, the endpoints
participating in the call can exchange (H.225)
call signaling messages directly between
themselves.
When the call is done, each endpoint, in turn,
requests disengagement (DRQ) and is
granted disengagement (DCF) by the
gatekeeper.
ARQ Admission Request.
ACF Admission Confirmation.
ARJ Admission Rejection.
DRQ Disengagement Request.
DCF Disengagement Confirmation.
Bandwidth Control
Messages
With a BRQ, an endpoint requests a certain
amount of digital bandwidth for a call.
If the gatekeeper grants the request,
it returns a BCF message.
If the gatekeeper denies the request,
it returns a BRJ message, typically because all
allocated data channels are in use.
If a bandwidth request is rejected, it is possible
for a call to be conducted
BRQ Bandwidth Request
BCF Bandwidth Confirmation
BRJ Bandwidth Rejection
* RAS in H.323 has nothing to do with the Remote Access Service that
is used in ordinary TCP/IP networks.