Early adopters in North America should note very carefully which frequencies and modes are supported by a particular phone. For example, while the Nokia E90 supports GSM on the North American bands of 850 and 1900, WCDMA can only operate on the European 2100 band. WCDMA operation in North America requires either WCDMA 850/1900 or WCDMA 1700/2100. The North American 2100 band is incompatible with the European 2100 band.