They don't even need to play the free card, if they can come up with some kind of bundling deal. 50% off a decent smartphone with $30/month unlimited web & text with 1000 free minutes could be a dynamite deal for most folks. (Even if it's throttled after a gigabyte or so.)

You don't have to be free for the strategy outlined in the post, you just have to be too good to pass up. (Much like: A decent tablet for only $200.)