Because the Whistle GO family of trackers use AT&T’s LTE network, AT&T coverage in your area is required. If you are not eligible for an upgrade due to insufficient coverage, we can recommend the Garmin Astro 320™. Rest assured that our #1 priority is your pet's safety, so we'll jump through any hoop to provide you that peace of mind! If you're not sure about AT&T coverage in your area, please email or call us at: 1-855-907-3348 (M-F 7am-4pm PST Sat-Sun 7am-3:30pm PST).