With all the crap that’s gone on (and still going on) between AT&T and Verizon, it’s safe to say that this is the last thing AT&T wanted to come out. According to a study that just came out, AT&T would have to spend approximately $5 billion US to get their network to the same level as Verizon and Sprint.
This probably doesn’t come as a surprise to anyone who actually owns an AT&T phone, given the almost constant problems with dropped calls, spotty service, and slow data speeds. The study also admits that AT&T has started to upgrade their infrastructure, particularly in the Bay Area, with positive results. This makes sense give the nature of their agreement with Apple.