Interesting project that unlocks the door and plays music based on the phone number that calls it. I would be a little concerned thought if someone spoofs your number. I wonder if they could do something else to make it secure. And paying extra for the phone line…hum…I do like they re-used an old PC and have tracking of whom opens the door.
http://www.instructables.com/id/eLab-Hackerspace-GSM-Access-Control-System/