We have been "geofenced" into the north of the Antarctica Wild Human Zone....


https://streamable.com/hob7
I live in a very hilly part of a National Forest -- it is indeed a "Dead Zone" -- neither my, or anyone else's phone "has service".

However, if I were to dial 911, the county sheriff would pick up, and I'd have perfect reception.

There is nearly a world-wide grid, but consumer products don't have access to it.

22 years ago in a remote part of Alaska, I saw "bars" on my phone, and tried to make a call. I got a message saying I was unauthorized to use this network. Today the phones are smarter -- they don't show bars to these networks, and don't let your phone access them.