MCK pbxgateway Administrator's Manual page 259

Appendix B
Voice Compression
The PBXgateway deploys voice compression in order to extend multiple
users across fewer data channels. The PBXgateway supports the following
voice compression algorithms: 32 Kbps ADPCM, 24 Kbps ADPCM and
G.729A. Depending on the voice compression algorithm selected, you may
need anywhere from 16 Kbps (G.729A) up to 40 Kbps (ADPCM 32) per
user.
Compression Algorithms vs. Corresponding Bandwidth Size
G.711 ADPCM 32
64 (72) Kbps 32 (40) Kbps
( ) Maximum value of the combined compression bandwidth and the signaling
between the Switch and Remote units. This number reflects both parties talking
simultaneously in a voice conversation. Under normal conditions, this number
will be lower.
Using the bandwidth management formula on the next page, you can
determine the total bandwidth necessary to support your application. If you
have excess bandwidth on your network circuit, your network terminating
devices could allow you to use that bandwidth to connect to a router or even
another PBXgateway. In order to accomplish this, you must have the multi-
port capability on your CSU/DSU. For more information on your network
terminating devices, please see the Network Terminating Equipment section
of the Application Notes & Quick Installation Guide.
ADPCM 24 G.729A
24 (32) Kbps 8 (16) Kbps
Issue 2.1 December 1999
B-3