You can call AT&T and tell them to turn off text messages entirely. I did that a long time ago. I use iMessage 98% of the time, and the other 2% goes through my

You can call AT&T and tell them to turn off text messages entirely. I did that a long time ago. I use iMessage 98% of the time, and the other 2% goes through my Google Voice SMS, so I no longer need the ability to receive in-bound SMS on the AT&T number. It's a move I've never regretted, and I'm thrilled to longer give a single cent to AT&T for absurdly exorbitant text messages.