Press *69 on the phone immediately after you receive the call,an

*69 is a call back function. It is a service package provide by the phone company and charge per use. If you don't have the service, you can call police and they will check it for you.

FBI官員表示，如果家中的固定話機收到不明勒索電話，可撥打“*69”查詢對方號碼，如果是手機接到該類電話，可立即掛斷，並撥打“*57”，然後再掛斷，電話公司會自動記錄來電號碼。