Chapter 10
Remote AT command by SMS
This feature is to control the modem to interpret AT command from incoming SMS, executing it, and return the result
to sender by SMS.
The user can enable the modem to receive AT command by incoming SMS.
10.1 Description of the operation
Figure 10.1.1: Example of remote AT command by SMS
1. 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+SMSAT command
(default key is "000000"),
(c) The 7th and 8th characters of the SMS content is "AT" (in capital letters).
2. 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.
3. When using SMSAT feature, only +CNMI:x,1,x,x,x setting could be used (i.e. incoming message will be stored
in SIM card).
4. The maximum length of the AT command is limited by length of SMS, i.e. 160-6 = 154 characters.
5. 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.
6. If response(s) of the AT command is (are) more than 160 characters, only the first 160 characters will be
returned.
7. In case the modem cannot get terminal response within 26 seconds, the modem will then abort the command,
and return intermediate responses (if present).
8. If the SMSAT feature is enabled, all incoming SMS, either with valid AT command or not, will be erased. This
clearing of SMS will happened after the 19
th
SMS is received. This is to prevent SIM card memory from fully
filled; such the modem will not receive new SMS.
Confidential, the whole document is the sole property of Maestro Wireless Solutions ltd.
support@maestro-wireless.com
55
To Next Page
Loading...
