[inquisitor]

Of course there's WCDMA (also called UMTS or 3G) in Austria and all four operators support it at 2100 MHz. As of the 1800 MHz-band allthough it has been specified as UMTS frequency band III I've never heard of any operator on this planet running a UMTS-network at 1800 MHz nor have I ever seen compatible user equipment. That's why I assume that your router supports GSM (GPRS/EDGE) at 1800 MHz but not UMTS. In Austria besides UMTS at 2100 MHz, they have widespread GSM networks running at 900 and 1800 MHz.
Anyway GSM is a 2G network technology with modest bandwidth (max. 236 KBit/s through EDGE), so GSM is only of interest if you move outside 3G-coverage. In this case it would be better if your device supported GSM at 900 MHz than 1800 MHz, which provides further range and indoor penetration due to the physical properties of lower frequencies.