this SIM5218 AT command manual - Cooking Hacks

SIM5218 Serial AT Command Set
Defined values
Integer type value which represents the incoming call ringer sound level. The range is from 0 to 4,
and 0 represents the lowest level, 2 is default factory value.
NOTE is nonvolatile, and it is stored when restart.
Examples
AT+CRSL=2
OK
AT+CRSL
+CRSL:2
OK
4.27 AT+CSDVC Switch voice channel device
Description
The command is used to switch voice channel device. After changing current voice channel device
and if there is a connecting voice call, it will use the settings of previous device (loudspeaker
volume level, mute state of loudspeaker and microphone, refer to AT+CLVL, AT+VMUTE, and
AT+CMUT), except microphone level (refer to AT+CMIC).
NOTE Use AT+CPCM command to enable PCM function and configure the mode that you want
before setting AT+CSDVC=4.
SIM PIN References
NO Vendor
Syntax
Test Command
AT+CSDVC=
Read Command
AT+CSDVC
Write Command
AT+CSDVC=
[,]
Responses
+CSDVC: (list of supported s)
OK
Responses
+CSDVC:
OK
Responses
OK
Defined values
1 – handset
SIM5218_Serial _ATC_V1.36 66
5/15/2012