Roger Cheng/CNET

AT&T is getting in on the data bonanza too.

The Dallas telecommunications company said on Saturday that it would double the amount of data on its shared data plans starting at the 15-gigabyte tier. The promotion, available to both new and existing customers, begins on Sunday and ends October 31.

The offer is just the latest promotion from a wireless carrier looking to both defend its base of customers and attract new ones from rivals. It comes at a time when No. 4 player T-Mobile leads the competition on subscriber growth and Sprint, the No. 3 carrier by subscriber, has shown new signs of life with a new CEO and several new programs of its own. Even top player Verizon Wireless has gotten into the mix by offering a temporary boost in data.

The difference with AT&T's plan is that the doubled data doesn't go away after a specific period of time. Customers who sign up will keep that their extra data for as long as they remain on that particular plan.