If we can manage to put the phone into hotspot mode and connect the ESP32 to it in order to send the message to twilio it could be router-less. In theory it works because you don't need internet access on the phone to receive a GSM text ... but not being able to browse with the phone will mean not being able to show a pretty UI.
If we can manage to put the phone into hotspot mode and connect the ESP32 to it in order to send the message to twilio it could be router-less. In theory it works because you don't need internet access on the phone to receive a GSM text ... but not being able to browse with the phone will mean not being able to show a pretty UI.