Robocall prevention

Robocalls are overwhelming the telephone network. An estimated 58.5 billion robocalls were made to U. S. mobile phones in 2019, a new record, and a 22% increase over 2018. Despite increasing efforts, the problem is only getting worse.

Unwanted robocalls annoy subscribers and make them reluctant to answer their phones.

TransNexus offers a suite of software products to protect your customers from unwanted robocalls.

These products provide several methods of preventing robocalls from flooding your network and bothering your customers:

  • Robocall dynamic traffic analysis
  • Reputation service
  • Blacklist to prevent neighbor-spoofing
  • Customer-maintained blacklists
  • Shield detection of high-risk and invalid numbers
  • Secure Telephone Identity (STI) using STIR/SHAKEN

Robocall dynamic traffic analysis

This is a type of fraud detection that’s designed to prevent robocalls. It counts calls from a specific calling number over a 60-minute period. If the number of calls from a number exceeds the trigger threshold, then the software will perform the action you chose during setup: either block the call, divert it to another call handling system (like our CAPTCHA gateway), or complete the call and log it in a report for your review.

Reputation service

This service checks the reputation of the calling number. Many people use smartphone applications and services that provide the ability to report robocalls. This crowdsourcing is used to build databases of robocall caller IDs. When enough people report robocalls from the same calling number, that number eventually acquires a poor reputation.

With the reputation service, you can set up policies that will either block call from a number with poor reputation, divert it, or report only. For example, some carriers have set it up to divert calls from a low-reputation calling number to the customer’s voicemail. Alternatively, you could divert such calls to the TransNexus CAPTCHA gateway, which would prompt the caller to enter a two-digit code. A robocall program would not be able to do that. Legitimate callers would hear the prompt, enter the code, and their calls would be sent through to you..

Blacklist to prevent neighbor-spoofing

The whitelist/blacklist service has powerful capabilities that can be used for a variety of purposes. One use is to screen calls when the calling number is like the called party’s number.

This trick, called neighbor spoofing, has become common in robocalls. The perpetrator is hoping that the called party might be more likely to answer a call from such a number—what if it’s from a friend or family member who’s in trouble and is trying to get through? So, they answer the call—anyone might—just as the perpetrator hoped.

You can blacklist calls that arrive at your peering SBC where the calling number is assigned to your OCN/SPID. Normally, such calls would be internal to your network. If they arrive from the external network at the edge of your network, they probably involve neighbor spoofing. Blacklisting your own OCN/SPID at the edge of your network can block a lot of robocalls.

You can set up the blacklist to divert such calls to the TransNexus CAPTCHA gateway.

Customer-maintained blacklists

Our software products provide APIs (application program interface) that you can use with your customer web portal to allow your customers to set up their own blacklists. You would need a web portal that authenticates subscribers before they can enter a request to block calls to their number from a specific calling number.

Shield detection of high-risk and invalid numbers

TransNexus maintains a database of high-risk numbers compiled from many sources. These numbers include premium-rate numbers, for example, and numbers known to be used in robocalls. You can enable the Shield service to block, divert or report those calls to protect yourself from robocalls and fraud attacks.

The Shield service can also identify invalid calling numbers. You can configure similar responses when such calls are detected. For example, the CRTC has mandated that terminating service providers in Canada block calls with invalid calling numbers. The Shield service makes this easy.

Secure Telephone Identity (STI) using STIR/SHAKEN

Robocalls are like a game of cat-and-mouse. Perpetrators are clever in finding an opportunity, then exploiting it until it gets blocked. Then they move on to another opening and continue. There are many techniques to minimize robocalls, but it has been difficult to completely shut them down.

But there is a way. There’s an initiative called Secure Telephone Identity (STI) that would eventually shut down robocalls completely.

This initiative uses technology like secure internet—HTTPS—with a system of attestation, certified signatures and verification. Sounds complicated, but the internet you use every day has employed technology like this for years.

Secure Telephone Identity would eliminate caller ID spoofing and robocalls.

The telecom version is called STIR/SHAKEN. These James-Bond-inspired acronyms describe a framework where the originating service provider attests to the validity of caller ID information and adds a secure signature. At the other end of the call transmission, the terminating service provider checks the attestation and verifies the signature.

This way, you would know whether the caller ID you see is fake. Robocall perpetrators would not be able to trick you. The terminating service provider might send a call with weak attestation through to you anyway, with an indication that the caller ID cannot be verified. But you might not answer that call. Eventually, robocall perpetrators would find that no one is answering their calls anymore. Game over.

TransNexus has added STI using the STIR/SHAKEN approach to our ClearIP and NexOSS software products. They’re production-ready today.

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Let us show you how easy it can be to get started with robocall prevention. Sign up for an interactive demonstration today.

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