I recently had an in depth conversation with the engineering team over at nofence. I learned some interesting things that they really should advertise. While it uses cellular signal for uploading map information to the device, it uses gps for the actual fence triangulation. They dont have great gps accuracy, about 4 feet, but it doesnt require a constant cell signal to operate. it uplinks once every 15 minutes to upload grazing patterns and location to the app, and verifies fence location. if it cannot connect it just keeps current data on fence location and tries again later.
