Back in the day, AT&T offered a rollover minutes feature that would carry your unused voice minutes from one month and tack them onto your total for the next month. Now AT&T is bringing back Rollover, but this time it’s applying it to data.

AT&T Rollover Data will launch on January 25 for all new and existing Mobile Share Value customers. As its name suggests, Rollover Data will let you carry your unused data from one month into the next. The feature will be free to all Mobile Share Value customers.

Now, for the fine print. If you have any Rollover Data, you’ll begin to tap into it once you’ve used up your monthly data allotment. Rollover Data will expire after one billing cycle or when you change your plan, including if you make a change to your data amount. Finally, AT&T says that Rollover Data is shared by all of the lines of a Mobile Share Value plan.

When Rollover Data launches later this month, AT&T will be the second major U.S. carrier to begin offering the feature, along with T-Mobile and its Data Stash offering. Because data is so important to the growing number of smartphone users and all of the apps and content that they consume, it’s nice to see the concept of rollover data finally becoming a reality among the major U.S. carriers. Here’s to hoping that it continues to spread.