I skimmed the paper and wouldn't take too much stock in it. One glaring issue I see is that the "control" for their analysis is another cell network that is absolutely tiny by comparison and services a completely different population from AT&T, so they're not really isolating other variables, they're cherry-picking data and over-indexing on it.

The other thing that immediately jumped out at me is the format-- it sure looks an awful lot like an academic thesis, and the authors are a professor and a student who started this work during their undergrad. There's surely no way a respectable journal would publish this document in its current iteration, so why is it in the news? Weird.