Dear @Galo_Aguirre,
welcome to the Community!
This means that your Arduino is fitted with a SIM800 or SIM900 board ?
I have used such boards, to control some "home automation", but by using SMS's instead of DTMF.
I agree that the SMS is not a "real time" control, like sending a DTMF could be, but if you take a sigh to what I did, maybe you can adapt it to your needs ? Here below the link to my old post in which I used an old smartphone connected to Arduino by means of a BT instead of using a SIM800/990 boards (not so easy to use).
Cheers, Ugo.