I was wondering if it is possible to send via GSM protocol and appropriate AT commands, few data through a simple GSM call (witout using data traffic). For example my system is a PIC + GSM Module and it monitors and processes a string of data. When the user wishes, he makes a voice call in order to interacts with the GSM module via DTMF commands for example via an APP. My dubt is if the GSM module is able to send the data to thesmartphone in order to monitor the status of the system. The module is a Quectel M95. During some investigation, I saw that the module can send USSD codes but I don't know if it's possible to customize the USSD and read it from the smartphone as I wish. Or maybe is it possible to use the FAX for data exchange?
Thanks everybody in advance
Marco