Chapter 4 – Voice Commands
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434H)
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+VTX
Start Voice Transmission Process
Description:
Starts the voice transmission process. The PC sends the data in the format of the
previously eVSM command, using the flow control method selected by the
+FLO command. The voice data is buffered to withstand gaps of missing data from
the PC. If the modem does not have any current voice data, the modem sends
silence over to the analog destination until the PC provides more voice data. The
modem returns the OK result code and returns to Command mode after the modem
has completely transmitted its buffer contents. The Inactivity Timer can be used to
terminate the transmit data state, after which the modem returns to Command mode.
Syntax: AT+VTS
Result Codes:
OK on completion of transmission.
CONNECT if the modem accepts the command.
ERROR if the modem is not connected to at least one off-hook Telco line or one non-
Telco device.
+VGR
Voice Gain for Received Voice Samples
Description:
Sets the gain for the received voice samples. Receive gain values larger than 128
indicate a larger gain than nominal, and values smaller than 128 indicate a gain
smaller than nominal. The modem may limit the receive gain to a narrower range,
such as from 120 to 136, or from 120 to 128. The value 0 is reserved for modem
automatic gain control (AGC).
Syntax: +VGR=<gain>
Values:
0-255 Selects automatic gain control. Default is 128
Result Codes:
OK if <gain>=0
ERROR if <gain> is not 0 or if not in voice mode.
Reports:
+VGR?
Displays current or selected values.
+VGR=?
Displays list of valid values supported.
+VGT
Set the Volume for Transmitted Voice Samples
Description:
Sets the volume control, either by attenuating or amplifying the signal for the
transmitted voice samples.
Note:
The modem will limit the transmit level over the Telco lines, regardless of the
cVGT setting, to that permitted by CFR FCC Rules Part 68 –
Subpart D.
Syntax: +VGT=<level>
Values:
0-255 Selects volume for transmitted voice samples. Default is 128
Values larger than 128 indicate a larger gain than nominal, and values smaller than
128 indicate a gain smaller than nominal. The modem may limit the receive gain to a
narrower range, such as from 120 to 136, or from 120 to 128. The value 0 is reserved
for modem automatic volume control (AVC).
Result Codes:
OK if the modem accepts the command
ERROR if the parameter is out of range.
Reports:
+VGT?
Displays current or selected values.
+VGT=?
Displays list of valid values supported.
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