Years ago (before smart phones and data plans) I had a friend who signed up with Sprint at address #1 with free roaming on his plan. He then went to school at address #2 and used his phone mostly at address #2 where he was roaming because Sprint didn't have coverage. Sprint didn't like this, because he was costing them more money to roam than to use their network, so Sprint dropped him as a customer for roaming too much.

With our currently mobile population, I'm not sure everyone would like that. I have a phone number from a place I haven't lived in the past 6 years. I'm never going to change my number, and I know I'm going to move to a new place sometime in my life, probably more than once.

You have no arguments from me about T-Mobile's coverage, as a former T-Mobile subscriber myself, but you can't say it doesn't exist.

AT&T paid T-Mobile billions of dollars as a result of the failed merger, so they were going to supposedly use that to improve their network. I didn't notice an improvement.

Well, T-Mobile has LTE now (I use it). So it seems they used the cash to upgrade their existing network rather than expand it.