According to a new support page on its website, AT&T plans to increase the price of grandfathered unlimited data plans from $30 to $35 starting in February 2016. The company says this would mark the first price hike for unlimited plans, which are no longer offered to new customers, in 7 years. From AT&T:
Customers who have a grandfathered unlimited smartphone data plan will receive notifications of a $5/mo. rate increase for the data plan. The rate increase will take effect starting with the customer's February, 2016 service.
The company says that the plan itself isn't changing in any way, and customers will still be able to consume up to 22GB of data before their connection is throttled — a soft cap that was increased in September. If the rate increase causes you to want to jump ship, AT&T says that it will waive early termination fees for affected lines if you cancel within 60 days of being notified of the pricing change.