AT&T announced on Friday that the company will start to throttle the data speeds for the top five percent of data users from Oct 1, pulling the carpet on those who uses unusually large amounts of data.

"These customers can still use unlimited data and their speeds will be restored with the start of the next billing cycle," AT&T said in a statement. "Before you are affected, we will provide multiple notices, including a grace period. This change will never impact the vast majority of our customers, and is designed to create a better service experience for all."

AT&T insisted the change will not affect most of the customers. The company said they will alert the users with notices with and extend a grace period before they throttle the speed.

AT&T are yet to elaborate on how much data used will trigger throttling of the speed and how much the top 5 percent users are using already. However, the company said these top users on average use 12 times more data than average smartphone users.

According to the spokesmen, most of top data users were using their data for streaming large video and music daily, remote-webcam apps, send large files over the wireless web, or enjoy some online games daily over the wireless network, not Wi-Fi.

The company also strongly advised those concerned about their data usage to make use of their Wi-Fi when available since it does not "create wireless network congestion or count toward your wireless data usage."

Now, Sprint has become the sole major US wireless carrier that still offers unlimited data plan, with Verizon having changed to tiers and T-Mobile now throttling when users go over their "Unlimited" plan's 200MB or 2, 5, or 10GB limits.