AT&T on Friday said it would resort to throttling users with unlimited plans who burn through an excessive amount of data on a consistent basis.

As of Oct. 1, the top 5 percent of AT&T’s heaviest data users will experience reduced throughput speed, also called throttling, after their data usage reaches a certain point.

AT&T says that aforementioned 5 percent of users on average use 12 times more data than the average of all other smartphone data customers. The carrier said the change will not apply to the 15 million smartphone customers on a tiered data plan or the vast majority of smartphone customers who still have unlimited data plans.

In a press release, AT&T said that streaming very large amounts of video and music daily over the wireless network, not Wi-Fi, is what puts users in the top 5 percent of data users.

AT&T did away with its unlimited plans back in June of 2010. Those users who wanted to keep their unlimited plans were given the choice to do so. Users still on unlimited plans currently pay $30 per month, while the carrier’s customers on tiered plans currently get 2 GB for $25 or 200 MB for $15.

While AT&T said that this most recent step to reign in heavy data users is important, it will not solve the company’s spectrum shortage and network capacity issues. “Nothing short of completing the T-Mobile merger will provide additional spectrum capacity to address these near term challenges,” the company said.