The SMSAT feature integrated into SmartPack allows the modem to interpret AT commands from incoming SMS, executing it, and return the result to sender by SMS.
Description of the operation – SMSAT
- When enabled, the modem will treat the incoming SMS as a source of AT command only if all of the following conditions (a, b and c) are fulfilled:
a) The content of SMS sent to the modem is using standard 7-bit GSM data decoding scheme,
b) The first 6 characters of the SMS content matches the <key> parameter set by
AT+SMSATcommand (default key is “000000”),
c) The 7th and 8th characters of the SMS content is “AT” (in capital letters).
- If SMSAT is enabled, the modem will read each incoming SMS, if the conditions mentioned in 1 are matched the message will be executed, even it is an invalid AT command.
- When using SMSAT feature, only
+CNMI:x,1,x,x,xsetting could be used (i.e. incoming message will be stored in SIM card).
- The maximum length of the AT command is limited by length of SMS, i.e. 160-6 = 154 characters.
- When the SMS AT command is executed, all intermediate and final responses will be buffered recorded, then return to the sender’s phone number in one single SMS.
- If response(s) of the AT command is (are) more than 160 characters, only the first 160 characters will be returned.
- In case the modem cannot get terminal response within 26 seconds, the modem will then abort the command, and return intermediate responses (if present).
- If the SMSAT feature is enabled, all incoming SMS, either with valid AT command or not, will be erased. This is to prevent SIM card memory from fully filled; such the modem will not receive new SMS.
Example of use
<mode> is the configuration mode
0 disable remote AT commands by SMS
1 enable remote AT commands by SMS
2 change the value of the password <param>. Password is a 6 ASCII character key.
3 change the SMS response trigger. <param> is 0 to disable SMS response, 1 to enable it (default value).
//Disable SMSAT AT+SMSAT=0 //Enable remote AT command by SMS AT+SMSAT=1 //Set the password to be 123456 AT+SMSAT=2,123456 //Disable the SMS response AT+SMSAT=3,0
Limitation and caution when using remote AT command
- Never send ‘interactive’ AT command by SMS, e.g.
AT+CMGS=…. This feature cannot return the prompt to the sender for second input.
- Always wait for the return SMS with AT responses before you send another SMS AT command.
- It could be in some case (e.g. network failure) the modem cannot return response SMS. The modem will try sending response SMS for three times max. If still not successful it will abort.
- Always think twice before you send AT command by SMS. For example, if you send
AT+CPOFit will turn off the modem, and you need to go on site to access the modem to reset it.
- Some AT commands can’t be sent over SMS, such as: