AT&T is apparently on a mission to keep people from migrating to the Verizon iPhone now announced, and is doing a variety of things to try and keep customers.

One thing they are doing is giving a free extra 1000 rollover minutes to customers. Some people are getting invitations to this via text that say:

"You're a valued AT&T customer. We'd like to add 1000 bonus Rollover minutes to the mobile number ending in xxx. There's NO cost or obligation to you. It's our way of saying thank you. To have your minutes added, reply YES by 3/31/2011. Reply stop to end mktg msgs."

While not documented specifically, it appears that all you need to do is text 11113020 the word "yes"

At first, we were confirmed this may be a scam, but it does appear to be real, and we've tried it. It works on at least the iPhone (see screen shot).