AT&T is not actively limiting upload speeds for iPhone 4 users as some had feared, the company confirmed Wednesday. Users who have experienced significant slowdowns on their HSUPA connections are apparently suffering the after-effects of a software defect in the equipment AT&T is using in some towers. AT&T said that the problem should only be troubling less than two percent of wireless customers, and that a software fix is on the way.

Certain pockets of iPhone 4 users began reporting over the long weekend that their upload speeds were significantly reduced from the speeds they got when the iPhone 4 first launched. As chronicled by MacRumors, many of these users noticed that their uploads seemed to be capped at 100kbps—significantly lower than the several megabits they were getting a week prior—but that the problem appeared to be regional. Not all users in every city were seeing the same issues, indicating that it was likely an equipment problem.

(We Ars staffers here in Chicago continually checked our own iPhone 4 data speeds and found no noticeable speed degradation. As of Tuesday, I was consistently getting 1.2Mbps or higher in upload speeds, according to the SpeedTest.net iPhone app.)

It turns out the equipment theory was pretty solid: the defect lies in the Alcatel-Lucent hardware that AT&T uses, the company said in a statement sent to Ars. The problem itself is nebulous—AT&T merely said it was "jointly identified" by AT&T and Alcatel-Lucent, and that it was only triggered under certain conditions. Still, the issue "impacted uplink performance for Laptop Connect and smartphone customers using 3G HSUPA-capable wireless devices in markets with Alcatel-Lucent equipment," said AT&T. "While Alcatel-Lucent develops the appropriate software fix, we are providing normal 3G uplink speeds and consistent performance for affected customers with HSUPA-capable devices."

With that conspiracy theory laid to rest, affected users will just have to be patient and upload their YouTube videos at reduced speeds until they wait for a fix.