Tipped off by an anonymous tipster, Engadget brings word that AT&T is planning to axe its Messaging 1000 plan for individual users and leave behind just the unlimited plan, in a bid to simplify its offerings. The new plans are supposed to go into effect starting on August 21, 2011.

Come Sunday, Ma Bell intends to offer just the current Messaging Unlimited plan, where you get unlimited texting for $20 per month, and the pay-as-you-go plans, where you shell out 20¢ for every text message you send and 30¢ for every MMS. The $30 Family Messaging Unlimited plan, in all its unlimited texting glory, will also remain intact.

According to the accompanying screenshot in the Engadget article, the company believes that “the vast majority of our messaging customers prefer” the unlimited plan. For those of you who take an exception to that statement, however, it does intend to grandfather in those users who are currently on the Messaging 1000 plan.

Update: AT&T confirmed the upcoming changes in its messaging plans described above in an email to Engadget, adding that current users get to keep their existing plans, even if they change handsets. If you were planning to subscribe to AT&T’s $10 per month limited messaging plan, that’s your last window of opportunity right there.