Chapter 1: Overview
1-9
Hop-off PBX Calls.
Hop-off numbers are phone number patterns for calls to be routed out through
trunks. They are entered in a Hop-off Number Directory and associated with trunks where matching
calls should be sent.
Tenor BX
supports those hop-off PBX calls where the destination
Tenor BX
is programmed to route
the call to the PSTN via Trunk Circuit. (A hop-off PBX call is a toll call which hops through a pri-
vate network to reduce or eliminate the toll charge.) The destination
Tenor BX
unit is configured
with the phone numbers to be “supported” for this feature.
H.323 Gatekeeper Services
The
Tenor BX
unit’s built-in H.323 gatekeeper performs IP call routing functions, such as call con-
trol and administrative services to another
Tenor BX
unit, or another H.323 endpoint. The gate-
keeper’s functionality complies with the H.323 industry specifications for voice control and
management.
Gatekeeper
.A Gatekeeper in an H.323 network provides call control services and other services to
H.323 endpoints (i.e., gateways, terminals, and MCUs). The
Tenor BX
has a built-in H.323 gate-
keeper which complies to the H.323 industry specifications for voice control and management. The
gatekeeper performs call routing functions for calls entering and exiting a site.
The Gatekeeper performs IP call routing functions, such as Call Control Signaling and Call Authori-
zation for Gateways, IP phones, and H.323 terminals. The Gatekeeper communicates with other
Gatekeepers through a Border Element. When using a group of
Tenor BX
units, you can assign one
unit as the Gatekeeper for the network. We recommend you configure each as its own gatekeeper.
Tenor BX
supports gatekeeper to gatekeeper communication using the standard LRQ (Location
Request)/LCF (Location Confirm) messaging scheme.
Zone Management.
A zone is a group of H.323 defined endpoints controlled by a Gatekeeper. End-
points can be gateways (i.e.,
Tenor BX
), terminals, and/or multipoint conferencing units (MCUs).
Endpoints establish control channels with a gatekeeper for registration, admission, and security. Call
routing information about the endpoint is sent to the gatekeeper, including: IP address, unit type
(gateway, terminal, or MCU) and routing information (such as phone numbers, number patterns,
etc.).
A collection of zones is an administrative domain. An administrative domain provides call routing
services for its zones through gatekeeper to gatekeeper messages or gatekeeper to border element
messages (see below for more information).
Call Registration.
When registration from an H.323 endpoint is complete and a call is originated,
the call request is sent to the gatekeeper. The call request provides the Gatekeeper with the dialed
number and requests the routing information. The gatekeeper confirms the dialed number and sup-
plies the endpoint with the destination IP address. For example, a
Tenor BX
’s gatekeeper will act as
the gatekeeper for that zone and all of the other endpoints will register with it.
Border Element.
The
Tenor BX
’s gatekeeper uses a border element to gain access to the routing
database of the administrative domain for the purpose of call completion or any other services that
involve communications with other endpoints out of the administrative domain. The border element
functionality is built into the
Tenor BX
unit, along with the gateway and gatekeeper.
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