in hk it runs on gsm 900/1800
in canada it runs on 850/1900
msot hk tri band phones u can get is 900/1800/1900 so the thing is either way it'll work just how well and how much receiption u can get
for the best reception try to get something thats quad band but if not the newest one would be smartone vodfone tx80 which is pretty nice but not sure if its unlockable just yet ...
if not sx633 n73 w850 and d900 is the 4 most popular phones in hk right now