Longshine LCS-8156C1 - Manual (Page 189)

AT Commands for CX930xx Modem Reference Manual
102752B Conexant 5-25
+VGM - Microphone Gain
This command causes the modem to set the microphone gain of the speakerphone
function.
Syntax
+VGM=
Defined Values
Decimal number between 0 and 255 corresponding to the gain.
Reporting Current or Selected Values
Command: +VGM?
Response:
Example: 64 For the default setting.
Reporting Supported Range of Parameter Values
Command: +VGM=?
Response: range
Example: 0-255
Result Codes
OK = 0-255.
ERROR Otherwise, or if not in Voice Mode with speakerphone
enabled (+VSP=1).