goTenna - Text & GPS on Your Phone, no Service Required Bluetooth Low-Energy (BTLE) wirelessly pairs goTenna to your smartphone within approximately 20 feet. Long-range radio waves (151-154 MHz) radios and depends on terrain and elevation; up to 1 mile in urban settings and 4 miles in most outdoor terrain Use your iOS or Android phone to send texts & share GPS locations when there's no cell coverage or wifi available goTenna creates its own off-grid network with other goTenna users in the area Send private 1-to-1 & group chats or broadcast to all users nearby Free goTenna app includes free, detailed offline maps for any region in the world Sold in pairs