
Originally Posted by
damian_steele
Did you know that although companies shouldn't be given your unlisted phone number, they can legally buy lists of numbers which have been allocated geographically but have the final two or three digits missing? So if, for example, your area code was 01234 and your number was 567890 the company's list would show 01234 5678--. They then set their computer to dial the first set of numbers and increment the remaining digits from 00 upwards until someone picks up at the other end. The call is then handed off to a human operator who gives you the sales pitch. Or, if there is no operator free, you get an empty line (hence the silent phone calls).
So next time, instead of demanding to know how they got your number, you'll most likely already have your answer.