AT&T has introduced a new calling plan feature called A-List with Rollover. With this feature, you can add up to five most frequently called numbers to an "A-List", that you can then make and receive calls from at no additional cost. Those with FamilyTalk plans can add up to 10 numbers. And of course, since you won't be using any of your minutes with these calls, any unused minutes will rollover to the next month.
Individual customers with plans of $59.99 or higher are eligible for A-List, while FamilyTalk customers must have plans of $89.99 or more. To add numbers to the A-List, you need to enroll in AT&T's online account management. The feature will launch September 20, 2009. Other carriers also have similar features, like T-Mobile's MyFaves for example, but AT&T is the only one to offer rollover minutes.