I was looking to buy an unlocked phone to use in London. I'll be there for about a year. As I was searching for some phones online, I came across two types of unlocked phones - international and U.S. versions. Does anyone know what the difference between the two types is? Thanks for your help.
The difference is usually in the 3G (high speed Internet) bands available. Many phones with North American 3G (850/1900 for AT&T; AWS for T-Mobile US) also contain the UK 3G band (2100), but it is *much* rarer to find a phone in Europe with North American bands. So I suggest you get your unlocked phone in the US. As long as it is quad-band GSM as well (GSM 850/900/1800/1900), it will work on slower EDGE speeds even without proper 3G.
Of course your Droid is CDMA and currently there is no such thing as a CDMA/GSM dual mode Android, so if you want another Android (you know you do!) and the phone you buy here is intended to be used for your year in London and you like it... you can bring it back and use it on T-Mo or AT&T as appropriate.
So in total: If you want your Europhone to work in both London and the US on 3G frequencies, look for the following:
Either 1) UMTS 850/1900/2100 (if you want it to work on AT&T in the US)
or 2) UMTS AWS/2100, sometimes just written 1700/2100 (if you want it to work on T-Mobile US)