With Verizon Wireless, Sprint and Helio recently advertising unlimited calling plans AT&T must have felt left out. They have since announced their own unlimited calling plan, which will be available February 22 and cost just $99 per month. The plan will be open to both new and existing users but is going to be available for a limited selection of phones. AT&T’s unlimited plan will cover US based calls with no roaming or long distance charges. The plan will be open to standard phones only, PDA’s, smartphones and the iPhone are left out. Overall it seems Helio has the closest offer to unlimited, which includes both calling and data. Of course a calling plan technically is for calling.