After a embarrassing incident of being locked out of my house for about a half a hour. I decided that I needed a alternate mode of entry, and a simple garage door pin pad or hide-a-key would not suffice.
Internet of thing switches #internetofshit is in the right vein but too insecure I don't need a script kiddy in a foreign nation making my garage door go up and down for fun.
The phone phreak in me wanted to do it though DTMF tones but saner heads prevailed and I settled on a GSM switch
After a failure buying a Crap relay switching box on amazon that only operated on 2G which as of 12/31/16 AT&T has dropped support for I had to find something better.
I reached out to a Alibaba vendor and found a very nice unit that supports 4G service
The unit supports in depth configuration though a RS232 serial connection and their software it also has a digital input allowing for a sensor or a switch where it can notify you via SMS. The device can also output serial on receiving SMS contains a 5+hour battery and has excellent signal strength. The seller included a RS232 cable, usb adapter, and sim card size adapters.
To provide the the service I found the provider Truphone they have a prepaid global sim that has unlimited inbound calling and sms and as long as the number is interacted with once every 90 days it remains active pretty much indefinitely.
After configuring the device though the software I mounted it in the garage and connected it to the opener
Now I have a device with a phone number and access control list that provides a extremely out-of-band way to get into my house for less than $100. I have to say if your looking for something like this the seller has much more complex models with many inputs and outputs and Truphone has been extremely helpful for a essentially free service.