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Chapter 4 – Voice Commands
Multi-Tech Systems, Inc. SocketModem MT5634SMIxx Reference Guide (S000263C) 115
Command: +VSM=? Report Voice Compression Method
Result Codes: OK
Description: The +VSM=? command reports several compression method identifiers in one of two
ways: either 1) a compression method (for PCM coding) from the table below, or 2) a co-
operative identifier (non-PCM coding) used with other manufacturer's equipment.
Example: The following shows an inquiry about the modem support of compression and
other data. In this example, the modem reports that it supports two compression
methods.
AT+VSM=?
128,"SIGNED PCM",12,0,(7200-8000,11025),(127-129),(0-50)
132,"ADPCM/AQ",2,40,(7200),(128),(0-50)
The compression method identifiers for PCM coding display the general classification of
the compression method in the form <cmid>.
Non-PCM coding reports the compression method identifiers in the form
<cmid>/<author>, where <cmid> is the general classification of the compression method
and <author> is the source of the method. The source <author> may be a proprietary
method or it may reference a published standard. Each field limit is 20 characters. The
+VXT command starts a translation to or from a particular manufacturer's proprietary
voice data stream format to an unsigned (non-PCM) format.
Identifier
Description
Signed PCM Linear PCM sampling using twos complement signed numbers
Unsigned PCM Linear PCM sampling using unsigned numbers
A-Log/Author Compression using a-law
U-Log/Author Compression using u-law
DPCM/Author Differential Pulse Coded Modulation
DPCMAQ/Author Differential Pulse Coded Modulation with Adaptive Quantizier
ADPCM/Author Adaptive Differential Pulse Coded Modulation
VSELP/Author Vector Sum Exited Linear Predictor
RELP/Author Residual Exited Linear Predictor
CELP/Author Code Book Exited Linear Predictor
CVSD/Author Continuously Variable Slope Delta Modulation
TDHS/Author Time Domain Harmonic Distortion
ADM/Author Adaptive Delta Modulation
DM/Author Delta Modulation
APC/Author Adaptive Predictive Coding
ATC/Author Adaptive Transform Coding
SBC/Author Sub-Band Coding
GSM/Author Regular Pulse Exitation Long-term Predictor (RPELTP)
LPC/Author Linear Predictive Coding
EAPDPCM/Author Embedded Bit ADPCM
MP-LPC/Author Multi-pulse LPC
LSLTCQ Least Squares Lattice Trellis Coded Quantization
IS-101 does not make any provisions for standard compression modifiers.
Command: +VTD=<dur> Select Default Beep Tone Duration Timer
(DTMF/Tone Generation Duration)
Result Codes: OK if the modem accepts the command; ERROR if the parameter is out of range.
Description: The +VTD= command causes the modem to set the default DTMF/tone generation
duration used with the +VTS command. This command does not affect the ATD
command settings. The <dur> parameter range is given by the +VTD=? command, in
units of 0.01 seconds. A setting of +VTD=0 specifies a manufacturer-specific time
interval.