The mobile operator and exclusive provider for Apple's iPhone in the US said the upgrades are results of recent network enhancements, including the deployment of High Speed Uplink Packet Access (HSUPA) technology across all existing 3G markets that is expected to be completed by the end of the month.
Customers on the network should now achieved download speeds between 700 Kbps (kilobits per second) and 1.7 Mbps (megabits per second), up from 600 Kbps to 1.4 Mbps. Meanwhile, upload speeds should jump to the 500 Kbps - 1.2 Mbps range, up from 500 to 800 Kbps.
The announcement comes just days before Apple is expected to take the wraps off its next-generation iPhone handset which is widely expected to leverage 3G networks worldwide.
AT&T says its 3G mobile network is available in more than 275 major U.S. metropolitan areas, adding that later this month it will become the first U.S. carrier to have fully deployed High Speed Packet Access (HSPA) technology across its entire 3G network.
By year-end, the company plans to offer 3G service in nearly 350 major metropolitan U.S. areas.