Originally Posted by ScottC

Actually, GSM 1900 isn't RARE in Europe, it's not on a single network. All of Europe is GSM900 and/or 1800.

GSM 900 was the original GSM network frequency, in the mid 90's the first licenses were awarded for what was then called DCS, later GSM1800.

Later most GSM900 networks ran out of capacity and added overlay GSM1800 networks. So the networks that started on GSM1800 are 100% 1800 and the networks that started out on GSM900 now have a mix of both.

With most of the networks that operate on both, the GSM900 portion is mainly in the rural areas and along highways while their 1800 portion of spectrum is mainly used in cities to add capacity to their old(er) 900 network.

Of course, to make things complicated some countries are working on converting their old NMT450 networks into GSM450 networks.