They don't have any monthly subscriptions. It's all annual.
If you have a dedicated gps, you can get a chip for about $100/state. It needs to be updated periodically but once every 5 years is probably enough. They don't have satellite, though, just topo. I have a Garmin Montana with a chip that's probably 10 years old. You don't need cell service that way. I like the phone better, though, since it's lighter and more versatile.
