UMTS 850 in USA

[inquisitor]

Since 850MHz reaches farther and so requires less base stations, which renders network rollout cheaper, I expect that AT&T's 3G coverage is primarily based on 850MHz, while the 1900MHz-band serves only to extend capacity in urban areas with high load. Unfortunately AT&T's coverage map doesn't disclose frequencies and you'll hardly find user reports on the web, as your phone's frequency configuration is very exotic. Usually UMTS850-capable phones do support UMTS1900, too. Actually I don't know of any other phone supporting only UMTS850.