Have you been receiving a particular nuisance phone call?

I had these same phone calls over several weeks, as many as ten one day. Usually five or six. I have caller display,so when private caller came up or an odd number just let it ring. They never rang on Sundays. After making several enquiries was told never to answer as the calls were computerised and set to ring at intervals. If answered they knew you was home so flagged the calls,counted them, then used them for firms trying to sell stuff. If they did not get any answer after so long then did not ring any more. I have not had any more calls for weeks now so good luck.