It seems that AT&T has found the reasons behind the brutally slow upload speeds that iPhone 4 owners were experiencing the past few days. According to a report, AT&T is blaming a software fault in their network hardware that is powered by Alcatel-Lucent in some regions.

A fix is in the works, although no timetable has been released on when it will be released. Here's the official release from AT&T:

"AT&T and Alcatel-Lucent jointly identified a software defect - triggered under certain conditions - that impacted uplink performance for Laptop Connect and smartphone customers using 3G HSUPA-capable wireless devices in markets with Alcatel-Lucent equipment. This impacts less than two percent of our wireless customer base. 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."