How to Trace a Blocked Number

Caller ID has become ubiquitous on mobile phones and many wired phones as well, so you're right to feel concerned when you can't see the number of an incoming call. That's especially true if the caller turns out to be a repeat-offending prankster, an annoying telemarketer or – worse – a serial harasser. You can fight back and protect yourself by recruiting the help of your phone company or employing some simple-to-use smartphone apps.

How Call Blocking Works

Anyone with a modern touch-tone phone can block the caller ID function from revealing his phone number. The caller only needs to dial 67 before punching in your phone number. Telemarketers, collection agencies and robocallers often use more sophisticated technology to conceal their identities from you. Your phone's Call Return feature, activated by dialing 69, usually connects you with the last caller, but it does not function if the caller is using call blocking.

Contact Your Service Provider

When you've received unwelcome calls or texts from a caller who has blocked the number, ask the customer service department of your phone-service provider for help in identifying the caller. Your phone company needs the date and time of each call plus the specific nature of the offending message. Companies that block their identities when calling you may be prosecuted and fined if your number is registered with a Do Not Call list.

Get the App

With the right app, your iPhone, Android or Windows smartphone can trace a blocked number and give you a wealth of otherwise hidden information about your caller. Available for a monthly subscription fee, apps such as TrapCall, TrueCaller or Hiya not only provide you with a phone number, they may be able to tell you the caller's name and address immediately after you receive a call.

Protect Yourself

If your mystery dialer places an obscene call or makes a physical threat to someone in your household, let the police take charge. Hang up, wait for a dial tone, press 57 on your keypad, then wait for a recording that tells you Call-Tracing has been activated. Contact a local law enforcement agency and describe your complaint in detail. Your phone company will forward the unblocked phone number to your police or sheriff's office upon request. These procedures may vary slightly by region and phone-service provider, but the 57 code is utilized for this purpose throughout the U.S.