I don't ever get these calls, and my number is in PCCW's public directory. I have never registered with the "no junk" service. But I have set my line so that it will not accept calls which do not disclose their CLI (calling line ID). You can do this by dialling *76
See
http://www.pccw.com/eng/Products/For...l?sectionid=11 for details. Note that incoming international calls still get through because the network can recognise the difference between "number unavailable" and "number withheld".