three is a pretty big network in HK. you can pick up a 3network pay&go sim for about 15hkd, and the 100hkd (7quid) top up cards probably work out cheaper than using your uk phone.
one of the odd things I find is that it is cheaper to roam abroad, than call from the uk..
e.g. call phil from here its 1.20/min. call from spain & its 80p/min.
of course I always use the cheapdial number in the uk. but i rememeber running up about 10quid just listening to my voice mail in the singading
