Take care before retaliating to junk faxes along the lines suggested above. Most are designed precisely to provoke a reply ("Should there be more public holidays? Vote YES or NO"). Read the small print, and you'll find your reply is going to a premium-rate number and will be charged at an exhorbitant rate. (If there's no small print, you'll find out later.)

Most of the cost of your call goes straight to the firm running the scam. Many telecoms companies do little to discourage such practices, because their own profits are directly related to call volumes.