I got a few phone calls from all sorts of companies stating that I won a contest.
I remember I signed up for some stupid things online to get a free ipod or such, and ever since then, I noticed all these places from the U.S calling.
There's no way for them to stop calling.
But I did receive an email stating that they have failed to contact me via telephone so they are sending me an email.
In that email, there is the option to opt out of the advertising service. After that, they stopped calling!
Or, I usually tell them that they got the wrong number.