Robert is looking for a personal GPS tag for hiking and backpacking that can be used to locate someone in case of an emergency, but isn't tied to cellular. Leo says they are a very popular device for hikers, and the technology is called SPOT. It does GPS with their own satellite network, shows waypoints on Google Maps, and will alert family. Robert can check it out at FindMeSpot.com. There are also watches that use SPOT. Garmin's InReach has its own network.
Caller Gary in hour three mentioned the Personal Locator Beacon (PLB) which he can register with the federal government and they can use it to find people.