One can register with the Telephone Preference Service which does reduce the frequency of nuisance calls - but it does not stop them. In particular, calls originating abroad are not directly subject to this system which, I suspect, is one of these voluntary/self regulation set-ups. Also, there are some call centres in the UK which simply take no notice of the TPS. Finally, the recorded message types are increasing and I wonder if they are perhaps a deliberate trend to circumvent any detection by those trying to keep on top of the situation. I doubt if there is any equipment available to deal with this sort of thing unless it is simply not to re-act to caller numbers which are entered by the owner of the equipment/line. But then one would have to take the first call and after that blacklist the number concerned - withheld numbers would have to be ignored across the board, including those which one might actually want to take calls from.