AT&T will install its faster mobile broadband technology, which it calls HSPA 7.2, in six cities by the end of 2009, and in 25 of the top 30 markets by the end of 2010, the firm said today. Those cities are an odd mix of large and medium: Charlotte, Chicago, Dallas, Houston, Los Angeles and Miami. The company will cover 90 percent of its current 3G footprint by 2011's close.

AT&T's 3G network currently uses a 3.6 Mbps flavor of HSPA for downstream access, and either a 1.4 or 1.9 Mbps version for upstream transfers. The iPhone 3G and 3GS support only the older UMTS standard for upstream traffic and therefore max out at 384 Kbps.

The iPhone 3GS is capable of using 7.2 Mbps HSPA on the downstream side, but needs an enabled network. Several European networks operate at the faster HSPA rate. (The iPhone 3G supports just the older 3.6 Mbps downstream standard.)

HSPA 7.2 operates at 7.2 Mbps, including all the network overhead; individual users could typically expect to see between 1 and 4.5 Mbps of downstream speed, depending on a whole pile of factors. AT&T has said its HSPA 3.6 performance is routinely in a range from 700 Kbps to 1.7 Mbps.

AT&T is in the middle of spending tens of billions of dollars to upgrade its network, details about which it released in May of this year, and which I discussed in depth at my Wi-Fi Networking News site in "Hunk of Network Upgrade News from AT&T."

In unrelated news, AT&T is adding unlimited calling to numbers you pick at no extra charge, so long as you have a high-enough value subscription plan. Starting 20-Sep-09, A-List lets you pick five numbers on an individual calling plan of $60 or more (exclusive of data, tax, and other charges), or 10 numbers on a family plan of $90 or more. Numbers must be in the United States, but may be landline or cellular with any carrier.