In the UK, there has been a scheme called the telephone preference service since 1999. There is also a fax preference service and a mail preference service. I assume this is what has been alluded to earlier .

Since I registered I have not had a single call or fax. It used to be the faxes trying to sell me Viagra at 2am, (when I assumed that it must be someone calling telling me that a relative was ill) that annoyed me most. My mother in law broke her spectacles one-day rushing to get a call that she thought might be important. That double-glazing sales rep cost her a fortune. I hardly get any direct mail now, other than from companies that I have requested information.

So if you have any similar kind of service in your area, I would strongly recommend joining it.
http://www.tpsonline.org.uk/tpsr/html/default.asp
http://www.fps-online.org.uk/fpsr/html/default.asp
http://www.fps-online.org.uk/mpsR/html/default.asp