The battle over who has the fastest 4G network with most coverage is far from over, but recent outrage over slow upload speeds on AT&T might have given other carriers the edge. After users rushed in reports about upload speeds of less than a megabyte on the newly launched HTC Inspire 4G, AT&T replied that the phone simply doesn't support HSUPA. AT&T's 3G HSPA network consists of the HSDPA part for downloads and HSUPA for uploads. In our review, we found upload speeds to peak at around 150kbps, much lower than what the Inspire 4G should be capable of. What is the reason?
HSUPA is most likely present on the handset, but for some reason it seems disabled in the firmware, so a future update might fix the issue. Latest information by a source quoted by Engadget points to the 3GPP protocol as the main issue behind this. Currently, AT&T handsets authorize as 3GPP Release 5 devices on the network. This might not mean much to you, but what matters here is that the fifth version of the protocol doesn't support HSUPA. The updated 3GPP Release 6, however, does, and as soon as AT&T allows devices to authorize as Release 6, the magic of fast upload speeds will happen. There is one exception to the rule and not surprisingly it is the iPhone 4. The handset uses the sixth release, which grants it much faster uploads.
Well, this solves the mystery, but just when are the higher speeds coming? AT&T is believed to allow other devices to use 3GPP Release 6 within 1-2 months. So, let's wait up, it should be well worth it.