Chapter 3 System Features
DSP2 Voice Server Module
3-72
255-700-025
PacketStar
™
Access Concentrator 60 User Guide
, Issue 1
Release 6.3.0
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Soft permanent virtual circuit (SPVC) support for circuit emulation
service (CES). SPVC connections can be used for voice traffic on all modes
of the DSP2C Voice Server (A, B, and Echo Cancellation mode). This
feature allows up to 247 connections per trunk, with these restrictions:
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For voice transmissions over an SPVC connection to be successful, the
DSP2C at startpoint and endpoint of the SPVC must be configured with
the same values for all Voice Server features.
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SPVCs using voice processing features must be configured as non-
multiplexed.
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AAL2 multiplexing. The user can now multiplex up to 128 connections
on DSP2A mode or DSP2B mode, in up to 32 trunk groups; for echo
cancellation, the user can multiplex up to 224 connections in up to 32
trunk groups.
Software Features
The DSP2C Voice Server modules maintain required levels of voice quality
while conserving network bandwidth by using digital signal processor
technology to compress voice traffic.
The three modes configurable on the DSP2C are:
DSP2A Mode
. The DSP2A mode supports 128 channels of voice compression
meeting the ITU-T G.726 Adaptive Differential Pulse Code Modulation
(ADPCM) standard (40, 32, 24, or 16 Kbps).
DSP2B Mode
. The DSP2B mode supports 128 channels of voice compression,
meeting ITU-T G. 729A CS-ACELP (Conjugate Structure - Algebraic Code
Excited Linear Prediction) standared (8 Kbps). The ITU-T G.729B standard
for silence suppression is also suported.
Echo Cancellation Mode
. When configured as echo cancellation, the DSP2C
supports 224 channels of echo cancelled, uncompressed voice.
The interfaces of the DSP2C Voice Server module are configurable in any
combination of the three modes. PSAX Access Concentrator systems with
these modules process voice traffic entering the system on a number of DS0
circuits (channels) carried within the channelized DS1, DS3, STS-1e or E1
ports (ref. the Enhanced DS1/E1, Medium Density DS1, Channelized DS3,
Channelized STS-1e, HD-E1 Input/Output modules).
Table 3-9 below summarizes the three modes and their features available on
the DSP2C Voice Server module in multiplexed and non-multiplexed AAL-2.