In my case, they were contracted by the PC party of Ontario (might have been the party itself, but I doubt it) asking if I was intending to support them.
I politely declined to participate in their survey and asked to be removed from their calling list. The caller immediately initiated the removal process and provided me with a confirmation number of the removal without further prompting or explanations.
Granted, I wish they hadn't interrupted me at dinner time with an unsolicited call in the first place, but at least they were responsive with the removal request. Unfortunately, this particular call, while annoying and inconsiderate, was legal because it was a political call. I'll be blocking the number anyway, but this might not be an option for everyone. Make sure you ask them to remove you before the call ends, if you bother to pick up.
I LOVE my Panasonic phones. This number calls me frequently, but they should be gettin the message now. My phones pickup the call, and holds it for one second, then hangs up.
Get yourself a phone with call blocking. And because it picks up the phone, they get charged for the call. I lnow they only get charged pennies, but if millions do this, it gets expensive fast for the caller.