Verizon took top honors late Monday in a study of 3G data performance across the US. The tests, performed across 13 cities one day this past spring for PC World, show the carrier's EVDO-based network being the fastest with an average of 951Kbps downstream but also still fairly reliable with 89.8 percent of tests showing uninterrupted performance. Sprint was next closest with a significantly lower average speed of 808Kbps but higher reliability, at 90.5 percent.

The best connections varied by region, with Verizon more likely to provide strong access in East coast cities and Sprint more likely to help in the West.

Of the three providers covered in the tests, AT&T was noticeably degraded compared to the other two. Its download speeds were slightly better than Sprint's at 812Kbps, but its average reliability plummeted to 68 percent. Connections were particularly unstable or non-functional in the most significant coverage areas such as New York and the Bay Area, where reliability fell to between 60 and 65 percent. In Orlando, that figure dropped to a very low 52 percent. Only central US cities fared well.

Much of AT&T's poorer performance has been attributed by the company to its dependence on 1,900MHz wireless for 3G. The higher frequency offers less bandwidth and has a harder time reaching indoors or coping with interference; a high ratio of iPhone users has compounded the issue by frequently exploiting the network. AT&T should move its most important service areas, including New York and San Francisco, to the much better-behaved 850MHz band within several months. Improvements to the backbones supporting these airwaves should also help.

Both Sprint and Verizon are more likely to avoid such issues both through different wireless spectrum but also their technology. Although EVDO will be phased out sooner and prevents both data and voice at the same time, it doesn't have to carry both data and voice as AT&T's network does today.