Specifications
SIM900 AT Command Manual       
SIM900_AT Command Manual_V1.03  153  12/24/2010 
 0-6 (when mic=0 or1 default value is 0; when mic=2 or 3 default 
value is 5) 
<mode> 0 close echo algorithm 
 1 open echo algorithm 
Reference Note 
For this command, please refer to actual model. 
6.2.49 AT+CAAS    Control Auto Audio Switch 
AT+CAAS    Control Auto Audio Switch 
Response 
+CAAS: (0-2) 
OK 
Test Command 
AT+CAAS=? 
Parameter 
See Write Command 
Response 
+CAAS: <mode> 
OK 
Read Command 
AT+CAAS? 
Parameter 
See Write Command 
Response 
This parameter setting determines whether or not the audio channel will be 
switched automatically to the corresponding channel in case of headset 
attaching or detaching. 
OK 
If error is related to ME functionality: 
+CME ERROR: <err> 
Write Command 
AT+CAAS= 
<mode> 
Parameter 
<mode>  
0  disable automatic audio channel switch function, the headset 
HOOK function is disabled; 
1 enable automatic audio channel switch function, the headset 
HOOK function is enabled; 
2 disable automatic audio channel switch function, the headset 
HOOK function is enabled. 
Reference Note 
z  For this command, please refer to actual model. 
z  The headset detection is still worked when <mode> is set to 0. In other 










