R2511-HP MSR Router Series Voice Configuration Guide(V5)

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Admission control
If the address of the called endpoint is available, the calling endpoint sends an Admission_Request (ARQ)
message, based on which the gatekeeper decides whether to allow this endpoint to join a call process.
This is how the gatekeeper controls admission. In the ARQ message sent to the gatekeeper, the calling
endpoint might ask for direct call signaling (see Figure 67)
or gatekeeper-routed call signaling
(see Figure 68)
. The gatekeeper finalizes the way of sending call signaling to the called endpoint and
notifies the calling endpoint of it through an Admission_Confirm (ACF) message.
Figure 67 Direct call signaling between endpoints
(1) ARQ
(4) Call Proceeding
Endpoint 1
GateKeeper 1
Endpoint 2
(2) ACF/ARJ
(5) ARQ
(3) Setup
(6) ACF/ARJ
(7) Alerting
(8) Connect
RAS Messages
Call Signaling Messages