this SIM5218 AT command manual - Cooking Hacks

SIM5218 Serial AT Command Set
4.21 AT+CMIC Microphone volume control
Description
The command is used to control the microphone gain level. When the Module restarts, the gain
level will resume as default values. The setting will be saved to nonvolatile memory after write
command is executed.
SIM PIN References
NO Vendor
Syntax
Test Command
AT+CMIC=
Read Command
AT+CMIC
Write Command
AT+CMIC=
Responses
+CMIC: (list of supported s)
OK
Responses
+CMIC:
OK
Responses
OK
ERROR
Defined values
Range from 0 to 15, and 0 is the lowest gain level.
When the audio output of device is handset, 14 is default value; when headset, 13 is default value;
when speaker, 4 is default value.
Examples
AT+CMIC=5
OK
AT+CMIC
+CMIC:5
OK
4.22 AT+CMUT Microphone mute control
Description
SIM5218_Serial _ATC_V1.36 61
5/15/2012