The 900mhz GSM band is allocated to the amateur radio service in the US, 902.0-928.0 MHz 1500watt(yes one THOUSAND five hundred real watts no mili or micro anything) is the max on 900! There has been talk and experimentation with using European GSM (maybe more in the 400mhz region) gear for modded HT radios but also for free networks in the US for anyone who wants to spend $5 to test and take an easy 25 question tech exam from an open national question pool. http://www.arrl.org/frequency-allocations https://en.wikipedia.org/wiki/GSM_frequency_bands