Have you ever gotten a call from an anonymous caller ID? Of course, you have! These pesky blocked number calls are not only annoying but can be a one-way street to a financially damaging scam or identity theft. In the most extreme cases, sinister people withhold their numbers to harass and threaten those who answer the phone.

Getting a threatening call from a withheld phone number can make you feel powerless. Can you go to the police if you don't even know who's calling you? How do you block a number that you can't see? The truth is that getting to the bottom of a blocked number isn't easy – but it is possible.

Reveal A Blocked Number With Automatic Callback

Blocking a number is as simple as dialing *67, but so is calling that number back and catching the telemarketer who won't stop offering you a Caribbean Cruise or Florida Timeshare. Most phone providers have an automatic callback service.

If you receive a call from an anonymous number, don't answer it. Dial *69 to return the call and see the number. If the line is available, your call will go through. If it's not, the service will actually try to call the number every minute for the next half hour.

Unfortunately, an automatic callback isn't available in all areas, and sometimes, withheld callers are actually diverting the location of their original call. In that case, it won't work. Even so, this service usually costs just a few cents, so it's worth a shot.

Trace A Call If A Blocked Number Is Harassing Or Threatening You

While you may not be able to get the exact withheld number, you can rest assured that the police can figure out who is trying to contact you by tracing the call. Call Trace should only be used in serious situations where someone is harassing or threatening you. Don't bother local law enforcement because you're annoyed with telemarketers or hang-ups.

To trace a call, answer your phone and immediately dial *57. You should get a confirmation tone and message if the trace was successful. You'll receive an error message if it was not. Keep a log of the date and time of these calls or you won't be able to retrieve the caller's information. After tracing the call, contact local law enforcement who can work with your phone provider to retrieve the records.

The only downside of Call Trace is that this option isn't available in every location or with every phone provider. It also incurs a charge which will show up on your next bill.

Use An App Like TrapCall To Discover Withheld Numbers

There are numerous apps around the web offering the service of revealing withheld numbers. Most of them are a total toss up – they don't usually work. TrapCall has been widely regarded as the preferred unmasking service with features in publications like Wired and The New York Times.

To unmask a restricted number with TrapCall, install the app on your cellphone. When a blocked number calls, decline to answer. In a few moments, you'll get a call back from the actual number. You can then opt to blacklist whoever is calling.

Sign Up For The Do Not Call Registry

Rather than spending a lot of time or effort figuring out who's on the other side of a withheld number, you may simply want to sign up for the National Do Not Call Registry. This removes your number from various telemarketing call lists. If you still receive telemarketing calls after signing up, you can report it to the Federal Trade Commission.