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Understanding the L2W-323 Gateway
This section covers a variety of topics aimed at providing you with an in-depth
understanding of how the L2W-323 Gateway and internal Gatekeeper operate.
The L2W-323 in the H.323 Network
The L2W-323 Gateway functions on the H.323 network as the translator between the IP
LAN endpoints and other standard-compliant terminals on public circuit-switched networks.
By providing protocol translation and physically connecting between packet-switched IP
networks and circuit-switched public service networks, the Gateway functions as a service
provider to other H.323 LAN endpoints dialing out to the WAN and circuit-switched WAN
terminals dialing into the H.323 LAN.
Note: H.323 endpoints include terminals, multipoint controller units (MCUs), and
gateways.
More than just a "translator" between H.323 endpoints and phones on the ISDN, the
Gateway provides other functions to LAN endpoints dialing out through ISDN and circuit-
switched WAN terminals dialing into the LAN. These functions include:
!" DTMF (Dual Tone Multi Frequency) detection and generation.
!" Call transfer for LAN endpoints.
!" Audio transcoding.
!" Echo cancellation.
Gateway Services
The Gateway WAN interfaces provide several types of connections including voice calls,
1B or 2B video calls, 128 Kbps, 256 Kbps, 384 Kbps and 768 Kbps video calls.
These connections are made available to LAN endpoints through Gateway services.
A Gateway service is the mechanism that allows a LAN endpoint to choose the type of
connection it wants to establish with a terminal or telephone on a circuit-switched network.
Gateway services define the maximum baud rate per channel, the nature of the stream (voice
or data) and the mode (restricted/non-restricted) of the call. Each service is identified by a
service prefix.
Dialing to a phone on an ISDN, PSTN or cellular phone from a LAN endpoint through the
Gateway is much like dialing from a local PBX extension to an outside destination. To
Understanding the L2W-323 Gateway
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