Move over, Verizon: AT&T may begin throttling the data speeds of its heaviest wireless users as soon as October of this year. The move remains unconfirmed as of yet, but sources speaking to 9to5Mac claim that AT&T will begin implementing a network congestion plan similar to other carriers in order to battle the 80x increase in data traffic it has seen since the introduction of the iPhone in 2007.

According to the site's sources, AT&T's throttling plan will mirror that of Verizon's, which was implemented in February just before the introduction of the Verizon iPhone. Under that system, Verizon reduces the data throughput speeds for the five percent of customers who "use an extraordinary amount of data." The throttling typically lasts through the remainder of the current billing cycle and returns to normal at the beginning of the next one, though under some circumstances, it's possible for the reduced speeds to spill over into the next billing cycle as well.

AT&T's system is expected to work the same way, with speeds being taken down a few notches for those who go over their data limits until the next billing cycle rolls around. The sources didn't specify what AT&T's data limit would be before it begins throttling users, nor did they specify the speeds users might be able to expect once the throttling switch is flipped. "[W]e’ve been told that 12,000 e-mails, 12,000 website views, 4 streaming movies and 5 hours of streaming music will start to put you close to that upper range of usage," wrote 9to5Mac.

When asked for confirmation of the throttling plan, AT&T spokesperson Seth Bloom declined to comment.

Despite AT&T's lack of comment, the development is hardly surprising. AT&T has spent years trying to deal with network congestion issues, and became one of the first major carriers to implement monthly 3G data caps last year. Other carriers are already beginning to throttle heavy users, so it makes sense that AT&T would decide to follow suit. Not only is Verizon already throttling heavy users, Virgin Mobile recently announced that it, too, plans to begin limiting data speeds when a customer downloads more than 2.5GB in a month. That plan will go into effect in October as well.

The news will undoubtedly be unwelcome to those AT&T users who max out their data limits on a regular basis, even though those people only seem to make up a small percentage of all data users on the network. AT&T claimed last year that 65 percent of its smartphone customers use less than 200MB of data per month, and 98 percent use less than 2GB, though, so the throttling plan should only affect the top two percent (or so) of users.

Update: AT&T spokesperson Jackie Vettorino reached out to us on Friday afternoon to confirm the company's plans. The throttling for the heaviest data users will begin on October 1, and will only apply to users who still pay for unlimited data (and not users who pay for the non-unlimited tiers). The company has also posted a statement about the change on its website, which reads (in part):