This is the ironic but very legitimate question AT&T is asking.
As Adam Thierer writes,
Whatever you think about this messy dispute between AT&T and Google about how to classify web-based telephony apps for regulatory purposes — in this case, Google Voice — the key issue not to lose site of here is that we are inching ever closer to FCC regulation of web-based apps! Again, this is the point we have stressed here again and again and again and again when opposing Net neutrality mandates: If you open the door to regulation on one layer of the Net, you open up the door to the eventual regulation of all layers of the Net.
George Gilder and I made this point in Senate testimony five and a half years ago. Advocates of big new regulations on the Internet should be careful for what they wish.