If you are interested in using Google Voice to open you garage, then read on.
Some time ago I did a Google voice integration in order to open my own Particle based garage opener.
I believe this integration can be done with your Garadget as well, since it’s using the same platform.
Here’s a link to the article describing how you could do the same.
There’s the video that shows this integration at work:
Note: It only works on Android.
Hope you like it!