GSM, which took over most of the world, was designed in Europe. It likely was based on earlier research, very probably intersecting with military-funded research.

I wonder if the typical "towers + backbone + terminals" setup is relevant for battlefield communication. I'd expect mesh setups to be more viable and more resilient.

Given the military emphasis on CCC, it's hard to imagine cell networks - even just as theory - not coming from the DOD in some way.

GPS was (is) a lot military. Militaries , first responders and aviation still depend on VHF and in cases HF radio.

Motorola was (is?) a serious player in VHF and HF, so the first cell phone probably wasn't directly DARPA but the overall company had a lot of background with that sort of thing.