AT&T said it will change the data plans and monthly allowances for some wireline broadband customers starting August 21.

U-verse Internet subs on tiers with speeds up to 300 Mbps will see their monthly data ceiling rise to 1 terabyte before overage fees are applied ($10 for an additional bucket of 50 gigabytes of data).

However, customers who bundle U-verse Internet with U-verse TV or DirecTV service and pay for services on a single bill, per the current policy, still get unlimited home Internet data for no additional charge.  Other U-verse data subs still have the option to buy an unlimited plan for an additional $30 per month.

Meanwhile, customers on GigaPower, AT&T’s fiber-based offering with speeds up to 1 Gbps, will be moving to an unlimited data plan.  AT&T has been pairing GigaPower with 1-TB soft caps that charge $10 for each additional bucket of 50 gigabytes, with a max monthly overage charge of $30.

Prior to the new policy, subs on tier with speeds between 768 kbps to 6 Mbps were fixed with 300 GB monthly data allowances, while 12 Mbps to 75 Mbps were set at 600 GB, and those on plans with 100 Mbps to 1 Gbps speeds were set at 1 TB.

“For customers with internet speeds below 12Mbps, this triples their current amount of data; for customers with internet speeds ranging from 12Mbps to 75Mbps, this nearly doubles their current allowance,” Cheryl Choy, AT&T’s VP of data and voice products, said in the announcement.

AT&T has set up a site where customers can estimate, monitor and manage their data usage. AT&T said it will start to notify customers about the updated policies on August 1.

AT&T is also just one of several ISPs to recently adjust broadband usage policies.

Comcast is testing a 1 TB usage plan and an unlimited data option in a subset of markets, with Chicago joining the mix August 1 (subscription required).

Alaska’s GCI bumped the monthly limit of “Red,” its 1 Gbps residential cable modem service, from 750 GB  to 1 TB.

CenturyLink is also testing a usage-based billing policy in Yakima, Wash., but has not committed beyond that.