started by Sprint back in 2009, AT&T has just announced that it'll start offering its customers unlimited calling to any mobile number in the US, regardless of carrier, starting tomorrow (currently, only AT&T numbers qualify). There are a few catches, of course: you've got to sign up, you need to be on the company's unlimited messaging plan, and you need to be on a "qualifying" Nation or FamilyTalk plan. Unlimited messaging runs $20 for individuals and $30 on family plans, so the perk isn't exactly free -- but for many, it should take a big load off the minute bucket. Follow the break for the full press release.
Update: AT&T's gotten in touch to spell out the qualifying plans -- they'll be the Nation 450 and 900 options along with FamilyTalk 700 or higher.