Longshine LCS-8156C1 - Manual (Page 173)

AT Commands for CX930xx Modem Reference Manual
102752B Conexant 5-9
+VTX - Start Modem Transmit (Playback)
This command causes the modem to start the voice transmission process.
Syntax
+VTX
Result Codes
CONNECT The modem accepts the command.
ERROR The modem is not connected to at least one off-hook
telephone line or one non-telephone line.
+VGR - Voice Gain Receive (Record Gain)
This command causes the modem to set the gain for received voice samples.
Syntax
+VGR= 0 (only valid number) selects automatic gain control
Reporting Current or Selected Values
Command: +VGR?
Response:
Example: 0 For the default setting.
Reporting Supported Range of Parameter Values
Command: +VGR=?
Response: range
Example: 0
Result Codes
OK = 0.
ERROR Otherwise, or if not in Voice Mode.