AT&T is now patching a software bug on Alcatel Lucent 3G network equipment that was slowing upload speeds on the iPhone 4. The device is the only smart phone on AT&T's cellular data network that uses HSUPA (High Speed Uplink Packet Access). Only HSUPA is affected by the problem, meaning download speeds do not suffer.
Laptop Connect cards also use HSUPA, so they are having the same upload speed problems as the iPhone 4. Previous models of the iPhone were not equipped to take advantage of superior HSUPA upload speeds. The AT&T upload speed problem was first reported by iPhone 4 users three weeks ago.
iPhones around the country were having trouble sustaining 100 Kbps per second in speed tests. HSUPA is capable of much higher speeds, and initial reviews clocked the iPhone 4 at 15 times this speed during uploading. HSUPA is capable of upload speeds up to 5.76 Mbps per second when working properly under lab test conditions.
News sites began to speculate that AT&T had changed its data policy along with new tiered data plans to cap the upload speeds on its mobile network. The company later denied this was the case. Speeds are temporarily capped at 384 Kbps (regular 3G upload speed) to tackle the HSUPA problem and will be restored. Currently, AT&T expects the network-wide software patch will happen gradually, until HSUPA is totally fixed in 2-3 weeks time.The problem reportedly affects only two percent of AT&T users, and Alcatel has stated that equipment on other carriers' networks is not affected by the bug. AT&T Wireless recently changed its data plan offerings on the iPhone 4 away from an unlimited model and now offers two different tiers of bandwidth. The smaller plan provides 250 MB of data monthly, while the top-tier plan has a 2 GB limit.