How to Trace Anonymous Phone Numbers

1. Let the call go to voice mail. A simple way to discover the identity of an anonymous call is to not answer the call, let it 'roll over' to your voice mail, and then listen to it at your convenience. Most callers identity themselves, their phone numbers and the purpose of their calls in voice messages.
2. Redial the call. Most landline phones have 'Redial' buttons, and most cell phones either have a 'Redial' button or a redial feature (contact the manufacturer, whose number is on the main page of their website, to inquire about redial features). The anonymous call must be the last incoming call for you to use redial. If the caller answers, politely explain you received an anonymous call from that number and would like to know who called. If you get a message, the caller may have identified himself and/or his phone number in it.
3. Press *69. In North America, most phone carriers provide this service for a minimal charge (contact your landline carrier or cell phone provider to inquire if they offer this code). Press *69 to automatically redial the last incoming call to your phone. If the caller answers, politely explain you received an anonymous call from that number and would like to know who called. If you get a message, the caller may have identified herself and/or her phone number in it.
4. Request Anonymous Call Rejection. Most landline telephone carriers provide an 'Anonymous Call Rejection' service for a monthly fee that automatically rejects blocked phone numbers. Callers hear a recording that the subscriber (you) does not accept blocked calls, and if the caller wishes to complete the call, he must unblock his caller ID. Contact your telephone carrier or cell phone provider (whose phone numbers are on your monthly statements) to ask if they provide this service.
5. Purchase an unmasking service. TrapCall is a service that unmasks (unblocks) anonymous calls, and displays the caller's name and/or phone number on your caller ID. For a free trial, go to Trapcall.com, press the 'Try Trapcall free!' button in the lower right of the web page, and follow the instructions.
6. Purchase an anonymous call blocking device. There are products, such as Call Silencer, that automatically screens anonymous calls. Although Call Screener doesn't unmask caller IDs, it forces anonymous callers to unblock their phone numbers if they wish their calls to ring through to your number.
7. Press *57. Most phone carriers in North America offer this fee-based call trace service to track anonymous, harassing calls. When you press *57 immediately following a harassing call, the phone company records the caller's phone number (however, this number is not forwarded to you). Instead, the phone company asks you to sign an authorization form before they give this number to law enforcement for further investigation.