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While regulation and standards bodies are increasingly tightening the screws on scammers using robocall calls and SMS phishing, also known as SMSishing, attacks to defraud consumers, communications service providers still need technology on their side to reduce the threat of robocalls. In this article, we break down technology solutions available today to reduce the threat of robocalls.

Traffic-based contextual analysis

A high number of SIP invite and cancel messages coming from the same caller ID (CLI) can be a strong indicator that a Wangiri fraud scam is infiltrating your network. Wangiri scams use an autodialer to call multiple people simultaneously and immediately hang up before they answer. The scam aims to entice those who see a missed call on their phone to call back, unbeknownst to them that they will be charged a premium fee for the call. This fee is then siphoned off to the fraudsters.  By identifying the high number of SIP invite and cancel messages and cross-referencing the distribution of call numbers from a single origin against the calls to the single destination number, carriers can detect fraud attacks quickly and block them.

CLI Test Calls

Scammers often use caller ID spoofing to mask their true location. Spoof numbers are used to look like a legitimate call, even your neighbor's, to increase the odds that the call will be answered. Test call generators (TCGs) can be used to test the origin of international calls and whether they match the CLI. When integrated with a fraud management system, the TCG automatically commands the test call, validates the CLI, and returns analysis of the detected spoof numbers being used for robocalls.


Hotlists have been one of the earliest mechanisms for tracking high-risk call destinations, IRSF hotspots, and high-risk premium-rate numbers. When combined with machine learning capabilities, and regular catalog updates, hotlists remain an essential tool in identifying known and emerging attack signatures so that they can be detected and defeated quickly.

Voice Firewall

Combined with an end-to-end Fraud Management System (FMS), a voice firewall can reduce robocalls by sorting good traffic from the bad, blocking unwanted calls, and keeping a carrier's voice network safe and secure from nefarious robocalls.

Mobileum's fraud management solution provides an end-to-end approach from fraud prevention to call blocking. By monitoring critical areas such as the following, carriers have the tools to proactively reduce the risk of robocalls infiltrating their network and scamming their customers:

- Robocalling traffic profiling

- Calling number scoring algorithms

- Detection of manipulated Caller ID

- Blacklist management

- Number ranges validation

- Digital signature validation through STIR/SHAKEN standards

For more information about how to reduce the risks of robocalls, please contact us.

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