Telecom Reseller: Block Fraud Without Blocking Business

AB Handshake’s Head of Strategic Partnerships, Anna Potapova, shares expert insights in Telecom Reseller on how operators can stop telecom fraud without harming legitimate traffic. The article outlines various key strategies, including real-time blocking, call-specific filtering, and end-to-end validation, to help providers protect both revenue and reputation.

Quality of service (QoS) means not just coverage, but protection from spam,vishing, and other fraud. When customers receive robocalls or spoofed calls from seemingly legitimate numbers, they lose trust in both the provider and the impersonated business.

CLI (Caller Line Identification) spoofing, IRSF, and other voice fraud continues to threaten the revenues and reputations of operators and enterprise alike. In 2023, telecom fraud caused $38.95 billion in losses. Enterprise-targeted scams, like Wangiri 2.0, (artificial call inflation), cost businesses billions annually.

As attacks intensify, operators face a dilemma: how to block fake calls without undermining legitimate traffic. Overblocking, due to broad measures like cutting entire number ranges, can reduce revenue and customer satisfaction. Underblocking allows fraud to thrive, generating billing disputes and customer complaints.

 

The goal is simple: block fraud, not business.

Three major changes) can significantly improve fraud control strategies: real-time blocking, call-specific filtering, and end-to-end validation.

 

Real-Time Blocking AND Unblocking

Call fraud attacks unfold in seconds, causing immediate harm to subscribers. Blocking based on fraud detected in Call Detail Records (CDRs) days, weeks, or even months later may be too late to foil an attack, and disrupts legitimate traffic after the fact. Fraud management systems (FMS) must operate at the signaling level, identifying and stopping fraudulent calls before they connect.

Even with real-time systems, persistent rules often remain active long after an attack ends, unintentionally blocking valid traffic. Dynamic systems should automatically unblock numbers or ranges once the threat subsides. This reduces service disruption and improves throughput of legitimate calls.

Despite concerns about integration, real-time blocking can be applied without affecting current routing, or interfering with network elements and existing fraud and security systems.

 

Block Calls, Not Numbers

Most firewalls and fraud systems block all traffic from affected A-numbers or entire ranges, even when the number itself is legitimate. A more precise method is A-to-B blocking which means blocking only calls from specific A-numbers or ranges to targeted B-number ranges, based on pattern analysis.

Even more precision can be applied with behavior analysis at the signaling-level. A highly accurate FMS targets individual fraudulent calls rather than applying broad restrictions to all traffic from an affected number or range. With false positive rates less than 1%, legitimate call traffic is unaffected.

 

Validate Call Authenticity, Not the Number

While many operators consult databases and number intelligence services, calls using Do-Not-Originate (DNO), non-assigned, and other invalid numbers only account for about 25% of fraud cases. The remaining 75% involve spoofed or misused real numbers that won’t be flagged with a database or number validation query.

Initiatives to authenticate caller identity like STIR/SHAKEN, out-of-band, and bilateral verification models are gaining traction. End-to-end validation compares call metadata between the originating and terminating networks to confirm the authenticity of each call. This method proactively detects spoofed or manipulated CLIs before delivery, eliminating associated fraud.

 

Optimizing for QoS

Validation is effective in detecting spoofing and related fraud, when available and interoperable across networks, but it isn’t enough on its own. To optimize for user experience and revenue assurance, operators must adopt real-time, granular blocking that:

• Detects and blocks fraud dynamically at the signaling level
• Blocks based on behavior and call patterns – not lists and ranges
• Unblocks numbers and ranges when an attack has ended

Quality of Service means protecting subscribers from spam and scams, without disrupting legitimate services. To protect revenues and the integrity of voice as a business channel for enterprise customers, operators must look beyond broad and reactive strategies, and embrace detailed and dynamic policies.