Pair to your phone and create your own signal. goTenna Mesh gives you text and GPS, no service required. Revolutionary mesh networking privately and automatically relays messages through other devices to extend beyond point-to-point range; the bigger your network, the stronger your communications.
I got the original version of the Gotenna (Off Grid Messenger) which is very good. I can communicate with someone out of the carrier reception area. Although we are living in a city with reliable Mobile coverage but we can’t guarantee one day the nearby station will be online all the time.