I don't recommend you do that. It is based on using Google Voice as the telephone service for your alarm panel's dial-up communicator. To do that, you'd have to dedicate a Google Voice account for that sole purpose, and not use it for regular telephone calling. I don't consider it reliable enough for that purpose.
This is 2018. The alarm monitoring companies are all moving off of dial-up, and converting to a combination of direct TCP/IP communications via a gateway device, and/or cellular radio communicators. You can do so much more with these solutions, including remote monitoring of the status of your alarm, viewing security cameras, and remote arm/disarm of the system.