Can't believe that this still happens, but I know it does
My business is all about Digital Media and I also recruit into GCHQ, the Home Office and a few UK Defence companies re IT Security people etc...
I work on a Mac so always laughed when we got these calls; would string them along and then once I got bored, mentioned the Mac and they hung up, so rude
We bought the BT 8500 Enhanced Call Blocker handsets mid last year; we're on the TPS register, but still got calls! We haven't had ONE bogus call/recorded call etc since we got the handsets and we don't even get the full usability of these phones as we're with Virgin and not BT. So, if you do get these calls, these handsets are very much a good way to rid them once and for all... I'd highly recommend them!