Holdouts of AT&T's "grandfathered" unlimited data plans are going to be slapped with another $5 rate increase, raising the monthly charges to $40.

The increase in AT&T rates comes following a previous increase of $5 imposed in February 2016. The grandfathered unlimited data plans jumped 30 percent in just under a year, The Verge reported. The new round of increase will take effect on March 2017.

AT&T's move is to drive unlimited-data plan holdouts to ditch their old plans to metered ones. Back in 2012, AT&T blocked Apple's Facetime to force users to move to metered data plans. As such, the company faced lawsuits and fines imposed by the FTC and the FCC for throttling and restricting connections of users subscribed to their legacy unlimited plans.

According to PC World, Verizon is in the process of weeding out data hogs that uses more than 200GB of wireless data per month. Sprint and T-Mobile though, still offer unlimited data plans to new subscribers, but both companies have reportedly bumped prices up.

Accordingly, AT&T's process is softer compared to Verizon's, however, it is clear that raising rates by $5 or more every year would make it more expensive to retain the grandfathered unlimited data plan in lieu of the new metered ones in the long run. Moreover, those who insist on keeping their grandfathered unlimited data plans will have throttled connections after exceeding 22GB of data within a single service period.

In 2015, AT&T attempted to set the data limit to as low as 5GB but the FCC intervened citing AT&T misled customers about "unlimited" data, even imposing a $100 million fine. Throttling is prohibited in current net neutrality rules, however, "reasonable network management" is allowed.

C|net reported that AT&T recently reactivated their unlimited data plan, however, there are strings attached. The report stated that the offer of unlimited wireless data could be availed by customers who also avail to its DirectTV or U-Verse TV services. The initial cost of the new unlimited plan is $60 and an additional $40 for each line with the fourth line free. Subscribers can connect up to 10 lines to their service.