When T-Mobile initially posted the specs for its new LG G2x Android phone, it appeared that the device could get fast 3G mobile Internet service not just on the frequency bands used by T-Mobile but also those of AT&T. That would be a first and seemingly future-proof the phone once AT&T took over T-Mobile.
T-Mobile's 3G is in the 1700MHz band while AT&T is inconveniently in the 1900 and 850 MHz bands (that's why my T-Mobile Nexus S phone can't get on AT&T's 3G band). But, alas, it was all a big mix-up. Engadget finally got T-Mobile to fess up with an official statement:
The T-Mobile G2x fact sheet, attached [PDF link], contains accurate information. The T-Mobile website is incorrect and we're working to correct it. The G2x supports 850/900/1800/1900 MHz for 2G/GPRS only, and supports 3G/4G UMTS/HSPA+ bands I and IV. The G2x does not support AT&T's 3G bands. This banding is hardware based.
-Engadget, April 27, 2011
The G2x phone is compatible with the 2100 MHz 3G band used in Asia and Europe.