International Bypass Fraud has been a long-standing plague to telecommunications industry revenues for many years. Bypass fraudsters offer to connect incoming international voice calls to local markets by redirecting them through Voice-over-IP (VOIP) gateways toward mobile or fixed line subscribers. The most common VOIP gateway is commonly known as a SIM Box.

2017 Estimated Fraud Losses by Type
Figure 1: 2017 Estimated Fraud Losses by Type (in $ USD Billions) (Source: CFCA)

SIM Boxes can be simple devices with wireless GSM chipsets or very complex systems of distributed nodes that virtualize SIM cards across national borders. In the end, an international voice call terminating to a local market is diverted through the SIM card in the SIM Box and connected as a local call, tricking the terminating operator into charging the call as domestic thus depriving the operator of higher value international termination revenue.

Test Call Generation (TCG) was one of the original methods developed to detect and combat International Bypass Fraud. The theory is pretty simple. After provisioning some test numbers in the terminating network, generate international calls from a large variety of international markets and services toward the test numbers. When the TCG test system receives the test call, it compares the incoming Calling Line Identity (CLI) phone number with the known originated phone number. A difference in the originated and received CLI indicates something is awry because a properly routed and terminated voice call will arrive to the terminating subscriber (B-Party) with the original CLI (A-Party) intact.

For many years, TCG was the answer to detecting International Bypass Fraud. Test calls with local CLIs detected are considered SIM Box and immediately blocked by the operator. Operators believed they had the silver bullet. Eliminate bypass fraud by outsourcing TCG services at relatively low cost and simple setup. Problem solved.

Fraudsters eventually develop many anti-detection schemes to avoid detection by TCG
Figure 2: Fraudsters eventually develop many anti-detection schemes to avoid detection by TCG

Unfortunately, international voice bypass fraud offers too much financial benefit to the fraudster for him to simply give up. Fraudsters eventually developed many anti-detection schemes to avoid detection by TCG. Anti-detection schemes include black listing, white listing, forking, decoys, and plain old internal fraud. As the capabilities of SIM Box technology increased and the anti-detection schemes developed, TCG effectiveness decreased significantly.

Today’s most effective Bypass Fraud control systems include TCG but offer more advanced layers of protection through big data analytics, sophisticated pattern matching, and machine learning. Where TCG once served as the heavy artillery in the fight against fraud, it now serves as a light lookout- scanning the horizons for signs of the enemy.

LATRO was the first solution provider to offer a multi-layered approach to Bypass Fraud protection. Our Versalytics system processes data from switching, billing, and signaling nodes within the network in order to rapidly and comprehensively detect, locate, and block SIM Box and other bypass frauds. TCG is a component of the overall solution since it offers additional insights on end-to-end interconnects that complement results from advanced analytics processes. But comprehensive detection and SIM Box gateway device classification requires more than simple test calls.

LATRO'S Versalytics Suite is the only solution that provides multi-layered approach to Bypass Fraud protection
Figure 3: LATRO’S Versalytics Suite is the only solution that provides multi-layered approach to Bypass Fraud protection

TCG is good for testing international voice interconnects. In addition to detecting voice bypass fraud, TCG can often uncover other issues within a telecom operator network related to equipment misconfiguration, abuse by interconnect partners, billing errors, and inter-networking problems outside the home network.

In many ways, TCG acts as an auditor to the overall fraud management system. Through detection sampling, it helps confirm automated analytics-driven detection algorithms, the relative levels of bypass activity in the market, the presence of bypass in off-network operators, and reveal potential new fraud schemes not provisioned within the current algorithms and rules.

TCG continues to have its place as a valid and useful tool in any operator’s strategy for eliminating bypass fraud. However, TCG should never be used as the only tool. It is probabilistic in nature- meaning a proportionally higher number of call attempts are needed to detect a higher number of fraud cases. Combined with Signaling and xDR analytics, the limitations of TCG are minimized and its benefits maximized. For this reason, LATRO includes an effective TCG component in our complete solution for best-in-class SIM Box and International Voice Bypass fraud control.

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