T-Mobile USA will soon let subscribers to its unlimited data plans use at least 50GB of data each month before risking slowdowns in congested areas.

All four major nationwide carriers slow down their heaviest data users when they connect to congested cell towers. But while Verizon Wireless and AT&T set the potential throttle point at 22GB, and Sprint at 23GB, T-Mobile is already letting customers use at least 32GB a month before risking slowdowns.

According to multiple reports, T-Mobile is upping that threshold to 50GB starting tomorrow. T-Mobile's support team confirmed on Twitter yesterday that the limit will be increased starting Wednesday this week, without saying what the new limit will be.

The T-Mobile support account deleted that tweet today, but AndroidCentral published an image of a T-Mobile notice saying that "the Fair Usage threshold will be increased from 32GB to 50GB for T-Mobile customers" on September 20. TmoNews also reported that it has a source who confirmed the new 50GB limit.

When contacted by Ars, a T-Mobile spokesperson did not confirm or deny the switch to 50GB but pointed out that T-Mobile's current limit of 32GB is already 10GB higher than the ones imposed by Verizon and AT&T.

T-Mobile has been raising its data slowdown threshold each quarter so that it applies only to the top 3 percent of users. But the notice published by AndroidCentral said the 50GB limit will be in use "every quarter," perhaps suggesting that it won't be raised again for a while.

UPDATE: T-Mobile confirmed the change to 50GB and said it will take effect on Wednesday, just as earlier reports suggested.

To use more high-speed data, avoid congested areas

Although the carriers prefer not to call it "throttling" and use more neutral terms like "data prioritization," the policies intentionally limit the amount of bandwidth available to heavy data users relative to other customers. Of course, everyone might get slower-than-normal speeds in a congested network area, but those who are over the limit will get even lower speeds than everyone else.

If you stay away from congested areas, you'll be able to keep using data at full speed after passing the usage threshold.

"In the vast majority of times and places, you will notice little if any difference," T-Mobile says. "In the small number of times or locations where there’s network congestion, you may notice reduced data speeds. This experience is due to our data prioritization practice, which prioritizes customers who use more than 32GB of data in a single bill cycle after other customers." (That notice will presumably be updated to reflect the new limit of 50GB tomorrow.)

Meanwhile, CNBC reported today that T-Mobile and Sprint are once again talking about a possible merger.