Find the Number of a Blocked Call

Receiving a blocked call can be anything from frustrating to frightening. These calls may be from unwanted salespeople or pollsters, pranksters looking for a laugh, or individuals threatening your personal safety. Handling this issue on your own is, while possible, both a significant technical challenge and a potentially expensive option. If your problem with blocked calls is more serious, your telephone provider and local law enforcement agency should be engaged to help you handle the situation safely and effectively. Please keep in mind that you should always exercise caution when dealing with unknown callers and should avoid escalating the situation without backup.

Steps

Setting Up a SIP Trunk to Monitor Your Call Data

  1. Get an Private Branch Exchange (PBX) account. One option is Asterisk, a free, open source software. Another is Switchvox.[1] A PBX converts your computer into a telecommunications device and will allow you to manipulate incoming call data to identify blocked callers.
    • Before embarking on this method ensure that you thoroughly understand the technical challenge it presents and the potential financial burden it incurs.
  2. Find a SIP trunk provider. A SIP (Session Initiation Protocol) trunk provider is a way to get a phone line via the internet instead of through traditional phone lines. In order to access all the information you'll need you must subscribe to an enterprise-level SIP provider, for instance Flowroute or Cisco's CallManager[2]
  3. Subscribe to at least one DID (Direct Inward Dialing) number. Your SIP Trunk provider will offer phone numbers for you to control and monitor. Call data monitoring requires one such phone number.[3]
    • All the call data coming in to this number will include the "masked" identity information from blocked numbers.
    • Once set up properly you will be able to forward your normal phone number to the SIP trunk provider phone number (to get the identity information you want) then forward it back to your normal phone line.
    • Any VoIP (Voice over IP) phone number can work with a PBX like Asterisk to "unmask" the blocked number but enterprise level SIP trunk solutions offer the most flexible ability to access and manipulate your incoming data.[4]
  4. Access the SIP trunk provider's configuration creator. Work within your SIP trunk provider account to generate lines of configuration code and implement through your PBX software.[3]
  5. Modify the configuration code. The configuration from your SIP trunk provider needs to be altered in order to display blocked caller identities. This is achieved by removing a few lines of privacy "masking".[3]
    • If you're still confused, check the references for more specific information.
  6. Set up Call Forwarding. Adjust the configuration code by inserting your normal phone number. Calls will now forward to the DID number, get "unmasked" by the software hack, and then forward back to your normal line, automatically identifying blocked callers as they come in.

Dealing With Unwanted Marketing or Solicitation

  1. Get on the "do not call" list in your area. Most regions have a registry of phone numbers that marketing companies are expressly not allowed to call. Find your region's version of this list and add your number. Although this may not provide a 100% solution to solicitation calls it is likely to reduce them.
    • Some "do not call" agencies allow for you to file a formal complaint after having your phone number registered for a period of time and still being disturbed by sales calls.[5]
  2. Talk to the marketers directly. In many instances, simply telling marketers to remove your phone number from their company's list can stop at least some percentage of the blocked phone calls you're receiving. If you'd like more information check out Ask Telemarketers to Stop Calling.
  3. Talk to your phone company. Depending on the situation, your telephone provider may be able to give you helpful advice about how to identify a blocked caller, get your phone number off other existing call lists, or to aid you in "unlisting" your number in their own records.

Dealing With Harassment or Prank Calls

  1. Keep detailed notes. Note the time and date the blocked call was received, and any other details you have about the call. If you end up needing assistance from either your telephone service provider or from law enforcement, both will be more willing to help if you can a establish a pattern and offer detailed records.
    • Keeping a record of what is said during blocked phone calls is also important. Heavy breathing and hangups should be noted, along with any background noises.
  2. Contact your telephone service provider. This can be a 3-digit number if you are using a cell phone or a 1-800 number for general customer service.
    • Your telephone service provider will help advise you and may even help you trace the call. In most cases however you will have to engage local law enforcement to determine the number.
    • Consider using a smartphone app designed to search, identify, and block many different kinds of callers. Truecaller is one such option available on all major platforms like iOS, Android, and Windows[6] while Facebook's Hello is another.[7]
  3. Give your records to law enforcement. If the situation is serious enough and the telephone provider cannot provide a full solution to the issue, inform and work with local law enforcement to identify the caller and to remedy the situation
  4. Work with law enforcement to trap the culprit. Once law enforcement is involved they may request your help in identifying the offending caller. Cooperating with law enforcement fully is your best bet to solve the issue safely and effectively.
    • Sometimes for a call trace to occur, you will be required to keep the blocked caller on the line for an extended period. During the call law enforcement should be on another line to help identify the individual making the call.
  5. Consider pressing charges. Consult your law enforcement contact and if still unsure consider seeking your own legal counsel. While pressing charges can be costly, it is sometimes the only way to end ongoing harassment.

Tips

  • Consider changing your phone number if you continue to receive unsolicited blocked calls. *Share your phone number only with people you trust and ask that they not share it without your express approval.
  • Consider working with your telephone provider directly to block all future calls from a specific number or to "unlist" your own phone number thereby making it less accessible.

Warnings

  • Never take the law into your own hands. While it can be tempting to confront an individual making calls from a blocked number, you may be risking your own safety. Leave this to either the telephone provider or to law enforcement.

Related Articles

Sources and Citations

  1. Jump up ↑ http://www.teledynamic.com/blog/switchvox-vs-asterisk-a-feature-comparison
  2. Jump up ↑ http://arstechnica.com/civis/viewtopic.php?f=21&t=1190173
  3. ↑ Jump up to: 3.0 3.1 3.2 http://www.fakecaller.com/how-to-find-out-who-is-calling-from-blocked-and-private-calls/
  4. Jump up ↑ http://www.cnet.com/news/hacking-caller-id-unblocking-blocked-phone-numbers/
  5. Jump up ↑ https://www.donotcall.gov/
  6. Jump up ↑ http://www.igeeksblog.com/truecaller-iphone-app-review/
  7. Jump up ↑ http://www.engineerscorner.in/facebook-introduces-hello-app-with-social-data-in-competitor-to-truecaller/
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