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PacketStar
®
PSAX 2300 Multiservice Media Gateway User Guide
, Issue 1
Release 9.0.0
Chapter 3 System Features
Voice Processing
•
Bearer traffic and CAS using AAL2, where CAS is carried in the same AAL2
channel as the associated bearer traffic
•
Bearer traffic and CCS using AAL2, where CCS for the control of narrow-
band services is carried in a specific AAL2 channel that does not carry
bearer traffic, within the same ATM VCC as the associated bearer traffic.
The V5.2 Protocol Primary Rate Access (PRA) Enhancement provides ISDN
PRA service capable of carrying voice and data traffic, while also maximizing
bandwidth. The PRA enhancement increases the number of channels to a
single D-channel and 30 B-channels, and enables a PBX to be connected to
an IAD via a PRA port. The PSAX system supports a maximum of 100 PRA
ports. DSP resources may be reduced depending on the number of PRA con-
figured ports.
The V5.2 protocol supports ATM VCCs using AAL2 connections for Loop
Emulation Service (LES) in support of ISDN PRA (PRA only) with Emulated
Loop Control Protocol (ELCP). Traffic from a given ISDN PRA interface is car-
ried as a full or fractional ISDN PRA channel with separate AAL2 channels
for each B-channel and the D-channel.
This feature is supported on all PSAX systems with redundant CPUn mod-
ules. The V5.2 application can be configured on the 21-Port High Density E1
Multiservice module. The DSP2D module must be present and configured for
the V5.2 application.
Voice Processing
The DSP2C/D/E modules can process voice traffic on selected DS0 circuits
within the DS1 connections of the PSAX system. The DSP2C/D/E modules
support AAL2 SPVC connections and PVC multiplexing for reduced call
latency. It can also protect facsimile transmissions by automatically turning
off voice processing and echo cancellation on any channel when it detects a
modem tone.
See the PacketStar PSAX DSP2x Voice Server Module User Guide for information
detailing the nine AlgoSets (algorithm sets) and the type of voice compres-
sion offered, if applicable.
Echo Cancellation
Near-end echo is caused by the transmitted voice signal on a 2-wire sub-
scriber loop being reflected back to the telephone receiver. It sounds like you
are talking to yourself. An echo canceller cancels the echo by sending the sig-
nal back to the receiver at the same amplitude but 180 degrees out of phase
with the transmitted signal.
See the PacketStar PSAX DSP2x Voice Server Module User Guide for information
detailing the seven AlgoSets (algorithm sets) and the type of voice compres-
sion offered, if applicable.
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