Text connection to a video

I recently read about a video company that had numbers on the real estate sign, and if you text those numbers it connects you to a video of that house. Does anyone know how this is done? 

I use a servive called Gumiyo. I upload a video to this service and hang a sign that askes people to text me. They receive all my listings and can see pictures, text, and video.

Hope this helps.

Thanks Peter for that I have contacted to see about adding it to our service. 

 Thanks Peter, that does help. I was under the impression that it was listed on the sign as "TEXT 3456" and only that homes video is seen. I am going to try Gumiyo and see how that works.