A plausible sounding person will ring you and tell you that you owe your telephone company additional money. He will request your credit card details and the 3 digit security number. If you don't believe him he will tell you that he will cut off your phone. If you doubt him he will tell you to make a call and surprisingly your phone is dead, you can't call out.

He then rings back and demands payment. If you doubt him he will give you the telephone company number and tell you to call it. If you do, surprisingly nobody knows what you are talking about.

IT IS A SCAM.

It works like this, the person who makes the call is the only one who can terminate it. He merely holds down the mute button on his end and can hear you trying to call out. You cant of course because the first call has not been terminated. When you give up, he rings you back and many people are fooled into giving the details. Now they are free to spend your money! Simple approach but effective.

Remember your telephone company will write to you not cold call for an outstanding bill.