FWIW, GSM900 was never widely adopted in the UK, distributors instead preferring GSM1800. The 934 crowd never got their bandwidth back to this day.
That's not right, surely? The first UK GSM licences (Vodafone and Cellnet) were 900, followed some time later by one2one and Orange on 1800. (At university, I could always tell the people on one2one or Orange. They had loads of free minutes, but the networks were sparse and 1800 was more readily attenuated by masonry, so they had to stand outside in January to make phone calls.)
The first GSM phones in the UK were 900-only, too: if you were on an 1800 network, you needed to be sure to buy a dual-band phone.
Vodafone and Cellnet (or were they O2 by then? I forget) obtained 1800 licences quite a long time later, and added 1800 base stations too - and made a point of telling their customers that they'd get better service if they had dual-band handsets.
900 is still in use - and operators are allowed to use both 900 and 1800 for UMTS now [PDF]. How widely, though, I don't know.