AT&T: new limits on 'unlimited' plans

AT&T Inc., citing limited availability of wireless spectrum, said Thursday that it will slow upload and download connection speeds for mobile phone users who use too much data even though they signed up for an unlimited data plan.

The carrier said speeds will slow for 3G (HSPA+) users who consume more than 3 gigabytes of data in a month. Users of 4G LTE phones will see their speeds slow when they exceed 5 gigabytes of data in a month.

The latest move follows a policy change in June, when AT&T began slowing speeds for users in the top 5 percent of consumption. With the changes announced Thursday, that policy is being abandoned. Previously,AT&T didn't slow speeds for unlimited data customers.

The changes do not apply to AT&T customers who are on tiered data plans.

AT&T said on its website that the change is in response to "soaring mobile broadband usage and the limited availability of wireless spectrum."

The Dallas-based telecommunications giant said it has seen a 20,000 percent increase in data consumption by its users in the past five years, and has gone from 7 million smartphones on its network in 2006 to 39.4 million in 2011.

In that five-year time span, AT&T says, it has spent more than $95 billion to build out its network, both wireless and wireline, and it plans to spend an additional $20 billion in network upgrades this year.