In quite a number of countries, UMTS is used on more than one frequency band. In the US, AT&T, for example, has UMTS deployed in both the 850 and 1900 MHz band. And when I am in the US I can experience the difference quite often. My Nokia N8 is a penta band UMTS device while my 3G dongle is triple band and only supports the 1900 MHz band in the US. So quite often, when I am indoor I can still get reasonable 3G coverage with my N8 over the 850 MHz band while my 3G dongle finds nothing anymore.
In Europe, O2 in the UK has deployed UMTS in the standard 2100 MHz band and in addition, in London for example, also in the 900 MHz band (for details see here). Network operators in France, Finland and perhaps in a few other countries also use UMTS 900, but for the moment only for rural coverage outside the bigger cities.
And now I've come accross another example, this time from Australia. Telegeography reports that Telstra and H3G have run a 2100 MHz UMTS network together for the past couple of years while Telstra has run it's own UMTS 850 MHz network in addition as its workhorse. With the common 2100 MHz network now being shut down due to H3G having been acquired by Vodafone Australia, the report says that Telstra will continue using UMTS 2100 in some places. Also, if I am not wrong, UMTS 900 is used in Australia as well by one of the other network operators. So it's similar as in the US, where UMTS is run on 3 different frequency bands (in the US, it's 850, 1900 and 1700/2100 MHz).
I'm dwelling on this a little bit because of the LTE frequency challenge arising these days with LTE being used in a myriad of different frequency bands which makes it hard building devices that will work across the world. But as the examples above show we have already arrived there with penta-band UTMS now required for truly global access. So countries like Germany, where LTE is already deployed in three frequency bands (800 MHz, 1800 MHz and 2600 MHz) are not all that much different from other countries using UMTS in three frequency bands. Not that this makes the issue any easier but it is an interesting way to look at it.