An anonymous reader quotes a report from Ars Technica: ATT is raising the price of its grandfathered unlimited data plans by $5 a month, the second such increase in the past year. The price increase affects longtime mobile customers who have held onto unlimited data plans for years after ATT stopped selling them to new subscribers. The latest price increase was reported by DSLReports yesterday, and ATT confirmed the move to Ars. "If you have a legacy unlimited data plan, you can keep it; however, beginning in March 2017, it will increase by $5 per month," ATT said. The unlimited data price had been $30 a month for seven years, until ATT raised it to $35 in February 2016. The price increase this year will bring it up to $40. That amount is just for data: Including voice and texting, the smartphone plans cost around $90 a month. ATT encouraged customers to move to one of its new plans, most of which have data limits, saying the newer packages "provide several benefits that our legacy unlimited plan doesn't." For example, the newer plans support mobile hotspot connections allowing a phone's Internet service to be shared with another device. ATT had stopped selling unlimited smartphone data to new customers and to customers who are switching plans, but last year introduced a new unlimited plan that's available only to people who also subscribe to DirecTV or U-verse TV.