I ramble on a bit here about that.
AT&T has always been a horrible company in my experience. I think the reason Elon went with them is that the cellular network they bought in LA were originally the first company to build out every pocket of Los Angeles back when they were the unestablished competitor, something like McCaw Cellular and Cellular One (my memory is poor), but as soon as AT&T bought them, they started mucking with and ruining the networks, making all the cell sites work worse (literally the same night AT&T took over, my cell service stopped working, whereas before it had been superb; I promptly dropped them in the middle of a contract using terms of service violation, which of course they protested but I didn't let them, and I immediately switched to Verizon, previously NYNEX Mobile or Bell Atlantic Mobile or something; I lived in NYC at the time). Verizon bought the telco RBOC carriers. T-Mobile built a third independent network. For many years, San Jose has had better coverage from T-Mobile than either Verizon or AT&T, but Verizon was always either first or second place in good coverage and quality there, and when they witnessed compatition from T-Mobile, Verizon upped their game too. AT&T doesn't even care at all (witness Apple's horrible idea to go with AT&T and the horrible network performance at that time); AT&T's competitive model seems to be to select business deals with entities which impose monopolies upon its customers. If I were a Tesla owner today, I'd not pay for their horrible crappy AT&T service, asking instead for a multi-band offering that gets coverage from all the bands and protocols that all the cell providers use, and then go between the likes of T-Mobile and Verizon; doubtless, the one-size fits all Tesla refuses to do something as sensible as that with their cellular module. If they open sourced the module interface, intrepid engineers could design their own local special modules if they liked.
