While the iPhone 3GS may stand for speed, the older UMTS chip used inside is painfully slow when it comes to upstream data transfer on 3G. After Rapid Repair completed a tear-down of the new device, Macworld reported that the iPhone 3GS was limited to 384Kbps in upstream data transfer due to the older chip inside. As it turns out, this chip was used in the earliest implementations of 3G on GSM carriers, and was in the previous iPhone 3G models.

Macworld invites readers to test this theory by using a site like TestMyiPhone.com; in all cases, regardless of downstream bandwidth, you will experience an upstream bandwidth of 384Kbps or less. We've tested this and have found similar results. Of course there are a few reasons for using the older chip, the main one being preservation of battery life.

via Macworld