GPS SmartSole is the thinnest GPS tracker in the world, taking advantage of a small device and small battery in order to fit in a shoe. For this reason, we employ a 2G cellular device which is small enough to fit and does not require a large battery to function. But 2G cellular coverage is no longer available to the USA consumer. Fortunately, GTX Corp partners with T-Mobile’s business division which still hosts a large 2G network nationwide- keep in mind, the original 2G network is still larger than the current 3G / 4G networks. The only challenge is that T-Mobile does not maintain a map of their 2G coverage area, therefore, the only way to know if GPS SmartSole will work for you is to buy it and test it in your area. If there is not sufficient coverage, you may return GPS SmartSole for a refund. Typically, out doors, in good cellular coverage areas, GPS SmartSole is pin point accurate and updates every 5 minutes (10 minute on Economy Plan). Outdoor accuracy is good to within 15 feet, less in most cases.