AT&T plans to offer faster wireless data connections on its 3G network to customers, including iPhone users, when it enables High Speed Packet Access 7.2 technology in a half-dozen cities by the end of 2009.

The upgrade delivers theoretical peak speeds twice that of the carrier’s existing 3G network. Deployment will begin in Charlotte, N.C.; Chicago, Ill.; Dallas, Tex.; Houston, Tex.; Los Angeles, Calif.; and Miami, Fla. By the end of 2010, AT&T intends to have HSPA 7.2 available in 25 of the nation’s 30 largest markets. And by the end of 2011, the nation’s second-largest wireless carrier hopes to have the higher speed data available for 90 percent of its existing 3G coverage areas.

“Our deployment of HSPA 7.2 and supporting backhaul connectivity will enable our customers to continue to ride the leading edge of emerging devices and thousands of mobile applications,” said John Stankey, president and CEO, AT&T Operations. “Our network is based on the predominant technology platform used by operators worldwide and has been tested by today’s most popular devices. That experience gives us an important advantage in developing and deploying new technologies to meet customers’ future needs.”

The new network speeds will allow iPhone 3GS users to take full advantage of their device, allowing theoretical download speeds of up to 7.2Mbps. In all, AT&T plans to have six HSPA 7.2-compatible phones available for customers on its network by the end of the year, as well as two LaptopConnect cards.

AT&T said that it will also be performing significant upgrades to its “wireless backhaul” in the process, allowing the network to support HSPA 7.2 and 4G LTE — the next generation of wireless broadband, expected to begin its roll out in 2011.