Hello,
Thank you for your question,
In this case you should use command "setdigout" information of all the SMS/GPRS commands can be found in our wiki:
https://wiki.teltonika.lt/view/FMB_SMS/GPRS_Commands
Information on a "setdigout" command can be found in this link:
https://wiki.teltonika.lt/view/FMB_setdigout
To send GPRS commands you should use CODEC12. Codec12 is original Teltonika protocol for device-server communication over GPRS messages.
Information describing CODEC12 and GPRS command is also found in our wiki:
https://wiki.teltonika.lt/view/Codec#Codec_12
If you find the wiki information not useful enough or unclear or if you have some specific questions please feel free to respond here, we will be happy to help you.
Regards, Teltonika Support.