But they don't target their biggest competitor, which is Verizon. They single out AT&T. Sprint should be next, but they ignore them too, which I can understand, but definitely not Verizon.
They single out ATT because ATT customers switching to Tmobile is the easiest. ATT customers have GSM phones they can easily bring to Tmobile. For Verizon customers, its a lot more difficult.
Plus part of it is a jab at ATT for the failed acquisition.
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If Tmobile acquires the 700Mhz A block, then all these building penetration issues will slowly disappear.