Specifications

SIM900 AT Commands Set
SIM900_ATC_V1.01 26 23.06.2010
ATL<value>
Parameter
<value> 0..9 volume
Reference
V.25ter
Note
No effect in GSM
2.2.11 ATM Monitor Speaker Mode
ATM Monitor Speaker Mode
Response
OK
Execution
Command
ATM<value>
Parameter
<value> 0..9 mode
Reference
V.25ter
Note
No effect in GSM
2.2.12 +++ Switch from Data Mode or PPP Online Mode to Command Mode
+++ Switch from Data Mode or PPP Online Mode to Command Mode
Response
The +++ character sequence causes the TA to cancel the data flow over the
AT interface and switch to Command mode. This allows you to enter AT
Command while maintaining the data connection to the remote server.
OK
To prevent the +++ escape sequence from being misinterpreted as data, it
should comply to following sequence:
1. No characters entered for T1 time (1 second)
2. “+++” characters entered with no characters in between (0.5 second)
3. No characters entered for T1 timer (0.5 second)
4. Switch to Command mode, otherwise go to step 1.
Execution
Command
+++
Parameter
Reference
V.25ter
Note
To return from Command mode back to data mode: Enter ATO.
2.2.13 ATO Switch from Command Mode to Data Mode
ATO Switch from Command Mode to Data Mode