There is at least ONE exception in the US: Firstnet. They primarily use AT&T’s towers, but they have some additional resources that other carriers don’t have - they have additional towers and entire network bands that other carriers don’t have access to. This allows us to still have coverage in natural disasters or network congestion times. In addition, if there’s a natural disaster that knocks out coverage, they have satellite-based trucks that stage DURING the disaster, then come online as soon as it’s over.

A few years ago, I had to ride out hurricane Ida in New Orleans (long story). The western eyewall passed directly over the house we were in, and the primary trunk lines coming into the city got destroyed by a cable tower that collapsed into the Mississippi. The next morning I had cell phone coverage when none of the other carriers had come back online yet. We didn’t even have power, but my phone worked perfectly.

You have to be a first responder to join - you have to be added by your department’s communications coordinator.