Harassed by Private No. Calls

Recently, I was harassed by private number calls.  It was not one of those cold calls from the banks, but from someone - who had to put down the phone when I answer the phone.  I do not know why my number was picked from this.  I called up my service provider - the customer service officer was very kind - and was told that there is no other way out other than to change my mobile phone number.  Reluctant to change my good ol' mobile number, I had to live with the nuisance calls from a stranger.

I spoke with my hubby on it. He advised that I could have tracked those private number calls and make a police report. You see, these private number calls are not usual - simply because it always occur around noon time - between 11am and 3pm. It is terribly annoying because the call comes, picked up and the caller just hung up the phone before saying anything!  I'm seriously deliberating if I should make a police report and have the mobile operator unmask the so called private numbers...