Multi-Tech Systems MT5634SMI V.92 Command +VSM=cml,vsr,scs,sel Select Voice Compression Method

	Chapter 4 – Voice Commands
Command	+VSM=<cml>,<vsr>,<scs>,<sel> Select Voice Compression Method
Values:	(see individual parameter descriptions)
Default:	(see individual parameter descriptions)
Result Codes:	OK if the modem accepts the command; ERROR if one or more of the following apply: 1)
	the any parameter entered is out of range, or 2) any of the four parameters are missing
	from the command string. If an error occurs, the modem retains the previous <sds> and
	<sdi> parameter values.
Description:	The +VSM= command sets the modem to a specified voice compression method, silence
	compression sensitivity, and voice sampling rate. The modem can maintain a different
	event detection capability for each compression method. This command allows the PC to
	set the amount of silence compression appropriate to a particular situation or application.
	For example, you may want to record your welcome message with the lowest amount of
	silence removal, with the goal of reducing distortion, meanwhile recording other
	messages with a more assertive silence removal, to limit disk space used for recording
	purposes.
	The parameter meanings are described below.
	<cml> is used by the PC to select a compression method. The valid range of values is
	from 128–256. The range of values from 0–127 is reserved for future standards.
	<vsr> is used to select the modem voice sampling rate from the set of those supported.
	The unit of measure is samples per second. See the +VSM=? command for the list of
	sampling rates supported by the modem.
	<scs> has different meanings in voice transmit and voice receive modes. In receive, the
	PC uses <scs> to select greater amounts of compression activity; larger <scs> values
	mean that the PC wants the modem to treat noisier conditions as silence. There is no unit
	of measure for this parameter; it merely represents a number in a range. 0 disables
	modem silence compression.
	In voice transmit mode, the PC signals the modem that the data stream was recorded
	with silence compression by selecting a non-zero value from within the valid range (the
	same value as receive). Unpredictable results can occur if you 1) enable silence
	compression for transmitting a voice data stream that was not recorded with silence
	compression enabled, or 2) you disable silence compression for transmitting a voice data
	stream that was recorded with silence compression enabled. You can modify the silence
	expansion with the <sel> parameter. The range of valid values is 0–255. The modem
	may limit silence compression sensitivity to a narrower range (e.g., 120–128). A setting of
	<scs>=0 disables silence compression.
	<sel> is used to modify the amount of silence expansion. This parameter represents the
	minimum amount of silence that the modem will expand a period of silence that was
	previously deleted with a non-zero <sel> parameter. A setting of <sel>=0 means the
	modem will not modify the silence expansion. The valid range of values is ____ - ____ in
	0.1second increments. The modem ignores the <sel> parameter if the <scs> parameter
	is 0 (silence compression disabled).

Multi-Tech Systems, Inc. SocketModem MT5634SMIxx Reference Guide (S000263C) 114