Another way to opt out is the charge for changing numbers.
I moved from CA to IL and wanted a local number. The rep said, "No charge." Now this was Nov 2005. I didn't go through with it then because there would be no forwarding message on my old number.
After waiting until mid-January, I called again. This time the rep said there would be a $15 charge (?) per line for the change--I have 4 lines. When told about the previous conversation of Nov. 2005, the rep said that the policy changed on Jan 1, 2006. I asked to be transferred to someone to cancel my contract. After telling that rep that if they could unilaterally change our agreement without notice or consent, then I could do the same, and I'm cancelling NOW.
However, they then changed my numbers for free--so I'm not out yet.
p.s. You can shut off all incoming text messaging, I know, I shut my daughter's off after running up a $400 bill. You do it on line for receiving and on the phone for outgoing.