AT&T has announced another price increase, this time affecting customers who are grandfathered into retired unlimited plans. The carrier says that prices will increase by as much as $20 per month starting in August.

AT&T says that the price increase affects “most” of its “retired unlimited wireless plans.” Here’s the full list:

• AT&T Unlimited & More Premium
• AT&T Unlimited Choice Enhanced
• AT&T Unlimited & More
• AT&T Unlimited Choice II
• AT&T Unlimited Plus
• AT&T Unlimited Choice
• AT&T Unlimited Plan
• AT&T Unlimited Plus Enhanced
• AT&T Unlimited Value Plan
• AT&T Unlimited Plan (with TV)

AT&T explains that if you have a single line of service on your plan, your monthly payment will increase by $10. If you have multiple lines, your monthly payment will increase by a total of $20. “This is the total monthly increase, not per line increase,” AT&T confirms.

AT&T is attempting to offset the pain of this price increase by offering affected customers additional high-speed data. As explained by Ars Technica, AT&T is also boosting the amount of high-speed data offered to these plans:

AT&T Unlimited Choice, Choice II, Choice Enhanced, Unlimited & More, and Unlimited Value plans will now include 75GB of high-speed data and 30GB of hotspot data. AT&T Unlimited Plus, Plus Enhanced, Unlimited &More Premium, and AT&T Unlimited (with TV) plans will now include 100GB of high-speed data and 60GB of hotspot data.

Notably, AT&T’s price increase comes just a few weeks after T-Mobile also increased prices for some of its older plans.

You can head to AT&T’s website for more details on the price increases coming to these plans. You can also do some algebra to determine whether it makes sense to switch to one of AT&T’s current-gen plans.