Just to add: the 3g/4g thing is carrier-dependent, as some carriers in North America have used the term '4g' as a way of marketing improved/enhanced 3g technologies. For example, HSPA+ is a big improvement over UMTS. Both are technically 3g. However, if you buy a '3g' phone from some carriers, then you get a UMTS phone; but if you get a '4g' phone from those carriers, then you get an HSPA+ phone.