Telecom Fraud Detection: Types, Risks and Prevention

In 2026, telephony remains a key attack surface with voice and SMS scams among the most common forms of fraud in telecommunications.

The widespread adoption of AI in telecom has made it easier for fraudsters to deceive subscribers, whether by cloning voices, spoofing caller IDs or generating convincing phishing messages. For telecom companies, this means revenue loss and eroding customer trust.

Read on to learn how telecom fraud detection and prevention works and how operators can prepare before an incident occurs.

What is telecom fraud?

Telecommunications fraud, or telecom fraud, refers to fraudulent and deliberate practices of misusing networks or phone systems to deceive people, steal money, disrupt services or bypass charges.

It affects both operators and their subscribers. For telecom operators, the consequences include revenue loss from inflated roaming charges, stolen customer data, reputational harm as well as legal and regulatory penalties.

Top 10 telecom frauds

Telecom, powered by 5G, AI, IoT and cloud, can suffer from various attacks. The most common types of telecom fraud include:

1. SIM swapping/jacking

Fraudster convinces a mobile telecom operator to transfer their subscriber’s phone number to a new SIM card. But here is the trick: they control it and can intercept the consumer’s phone calls, text messages and security codes. It is especially hazardous because it bypasses the SMS-based two-step verification.

2. SIM box fraud

A fraudster overseas calls via voice over internet protocol (VoIP). The call reaches the SIM box (multiple SIM cards) located in the victim’s country. Then, they use one of the SIM cards inside this SIM box to call the victim through the local cellular network.

3. Wangiri fraud

Fraudsters place one-ring call and hang up before the subscriber answers. The victim wants to know who was calling, so they call back, having no idea that they are being connected to a premium-rate line.

4. PBX hacking

Private branch exchange (PBX) is an internal phone network that connects employees via short extension numbers. Hackers get into it through unprotected access (like admin, maintenance number or voicemail). Then, they can dial any number (often international or premium-rate) and the calls go through the company’s lines.

5. Traffic pumping (IRSF scam)

The fraudster sets up a “free call line” with a small operator that charges high fees for incoming calls. The fraudster generates a huge volume of calls (made by real people or bots) to that line. The originating telecom operator (whose customers make the calls) must pay the small operator for delivering those calls. Then, the small operator splits the profit with the fraudster.

6. SMS phishing (smishing)

Smishing refers to fraudulent practices that involve sending text messages with fake links or urgent requests, tricking individuals into revealing personal information or downloading malware.

7. Vishing (voice phishing)

The attacker impersonates a trusted person (bank representative or the victim’s CEO). They create a certain urgency and force the victim to transfer huge amounts of money to an unknown bank account or share credit card details, login credentials or one-time passwords (OTP). A common tactic is warning that the access to the victim’s bank account will be blocked or denied unless they act immediately.

8. Telecom arbitrage fraud

Consider a telecom company that offers international calls to Sri Lanka. A fraudster poses as a legal intermediary. They divert calls to another country (where termination is usually cheaper) and scoop up the difference in price. The trick? The operator pays Sri Lanka’s rate, but the call never reaches Sri Lanka. Instead, it is answered by a bot or not at all.

9. Subscription fraud

Fraudsters use stolen credit cards, create fake identities using stolen or forged ID cards or passports or hijack phone numbers. The aim is to bypass security and sign up for subscription services.

10. Deposit fraud

It can begin with social engineering scams such as a fake job offer. Criminals lure the victim into transferring money to a foreign bank account. They can also use stolen card details to buy prepaid SIMs, which they then use to open bank accounts or launder money.

3 reasons why traditional telecom fraud detection methods are failing

Traditional fraud detection often falls short and modern operators investing in telecom software development services for 5G, IoT, AI and cloud computing need to understand why.

Three reasons stand out:

• Reactive approach: Reacting to fraud after it has occurred is not enough. Modern fraud detection should focus on real-time telecom analytics solutions and ML algorithms capable of identifying fraud patterns.
• Legacy systems: Old systems based on batch processing can’t leverage real-time data feeds and predictive modeling. In a 5G and IoT environment, where billions of sensors generate traffic data continuously, batch cycles create a wide attack surface for fraudsters.
• Fragmented architectures: If the billing doesn’t talk to CRM, the network can’t connect the dots if fraud happens. Each system sees only its own dashboard, completely overlooking how fraud can spread.

STIR/SHAKEN: call authentication standard explained

STIR stands for Secure Telephone Identity Revisited. SHAKEN stands for Signature-based Handling of Asserted information using toKENs. Both standards are used to prevent caller ID spoofing using digital certificates.

Think of a digital certificate as an online ID card. It proves who the organization is on the internet. Each telecom operator receives their digital certificate from a certified body.

How STIR/SHAKEN works:

1. A subscriber makes a call.

2. The originating operator assesses the caller’s trustworthiness and assigns a trust level. Levels include:

• Full (A): The operator knows the caller and authorizes them to use the calling number.
• Partial (B): The operator knows where the call started but cannot verify that the caller is authorized to call that number.
• Gateway (C): The operator knows which network the call came from but cannot verify who the caller is. This usually happens with calls coming from another country.

3. The caller’s operator stamps the call with the digital signature containing the calling number, called number, trust level, current timestamp, etc.

4. The call (with its digital signature) is sent to the terminating telecom company. It often passes through one or more other networks (e.g. VoIP) along the way.

5. The call is passed to the verification service.

6. The verification service initiates a multi-step verification process.

7. If everything is verified, the call receives a green light and is delivered to the recipient.

Telecom fraud prevention methods

There are several ways telecom companies can strengthen fraud prevention across their networks, systems and partner ecosystems:

• Tracking network behavior: Be vigilant for warning signs such as suspicious call routing patterns and unauthorized access to PBX systems.
• Deploying AI-driven real-time fraud detection systems: Analyze network data, calls and messages to catch threats in real time.
• Securing PBX and VoIP systems: Enable STIR/SHAKEN standards to verify caller identity and audit systems regularly.
• Strengthening identity verification: Enforce multi-factor authentication (MFA) and session initiation protocol (SIP) encryption to block interception attempts.
• Introducing dynamic blocking: Apply fraud scoring to stop fraud before it spreads.
• Implementing stricter KYC and MFA: Verify new users and business partners to prevent fake accounts from activating lines on your network.
• Deploying SS7 firewalls: Filter unauthorized signaling messages (e.g., location requests, call redirects).

Telecom fraud detection by operator type

Every operator approaches telecom fraud detection differently. MNOs focus on the network level, VoIP providers on the partner and signup level, and MVNOs on the identity and billing level.

MNO

MNO stands for mobile network operators and is the backbone of telecommunications. It owns the whole infrastructure. Examples include T-Mobile, Orange and Vodafone. They:

• Track signaling layer visibility: This involves analyzing the signaling traffic which doesn’t appear in call detail records (CDRs).
• Implement hybrid firewalls: These protect both for new internet-based phone system (SIP/IP) as well as for the old traditional phone lines (SS7/TDM).
• Provide network traffic traceability: MNOs can check numbers using callback and home location register (HLR) verification.
• Track industry threat feeds: Sources include GSMA IRSF Prevention service and threat data shared through the Communications Fraud Control Association (CFCA).

VoIP

VoIP stands for voice over internet protocol. It enables making and receiving calls over the internet, instead of analog phone lines. VoIP technology converts voice into data packets using the internet. Examples include WhatsApp, Zoom and Google Voice. They:

• Strengthen identity and account security: Digital ID verification, stricter MFA and more robust KYC are among the most common measures.
• Encrypt everything: TLS (transport layer security) locks down the call setup messages and SRTP (secure real-time transport protocol) locks down the voice and video.
• Track every step of the call: Capturing how each call starts, routes and ends provides a full audit trail across the provider’s own systems.
• Implement an IVR (Interactive Voice Response) into suspicious calls: VoIP can pause suspicious calls and ask the caller to press 1. A real person will do it, most bots can’t. The call is then flagged or dropped.

MVNO

A mobile virtual network operator (MVNO) doesn’t have its own infrastructure. Instead, it rents base stations and transmitters from an MNO. They:

• Strengthen identity checks at sign-up: This involves digital ID verification, stricter MFA, more robust KYC.
• Monitor new SIM activity: A new SIM that suddenly starts making tons of calls or sending loads of messages is a red flag.
• Set spending limits: Spending on international calls is blocked or limited.
• Watch mobile money transfers and payments: This covers P2P transfers, digital wallets and strange cash-outs. Hints from phone, SIM or identity check help identify suspicious activity.

Challenges in telecom fraud detection

Detecting fraud in telecom is hindered by various aspects.

First, evolving AI can both help and harm. While it can be used in pattern recognition, real-time analysis and incident reporting, fraudsters use GenAI to clone voices and create hyper-personalized convincing phishing, vishing and smishing scams.

The expansion of IoT and 5G networks adds another layer of complexity. As huge amounts of data flow continuously, it is very difficult to identify anomalies. IoT devices are often deployed in public locations, which makes them easy targets for data breaches, unauthorized access or device compromise.

Legacy infrastructure with fragmented data silos also creates a challenge. Billing, signaling, subscriber, CDR (call detail records) and network data live in separate systems. Attackers can exploit the gaps between these systems.

Finally, fraudsters can operate across various countries and operators. Data needed to verify the pattern cannot always be shared freely, so telecom operators can’t connect the dots. This stems from different data protection rules (GDPR, CCPA and others) and privacy regulations. What is allowed in one country is prohibited in another. That’s why fraudsters can roam more freely in the telecom sector.

To learn more about telecom fraud prevention, reach out to our team.

FAQ

What are the most costly types of telecom fraud for operators?

IRSF fraud, SIM box fraud, arbitrage fraud and Wangiri (one ring) scam.

How is telecommunications fraud detected in real time?

AI-powered fraud management systems in telecom collect and analyze CDRs, signaling traffic (behind the scenes conversation between networks), billing records and SIP message logs (call setup logs) from various network devices. They combine built-in rules for known threats with AI for suspicious behavior (anomaly).

What is IRSF fraud and how can operators prevent it?

International Revenue Share Fraud (IRSF) is a financial crime. Fraudsters generate artificial traffic to high-cost international or premium-rate numbers and share the revenue with the terminating operator. Operators can prevent it by implementing real-time fraud monitoring system and enforce strong access controls.

What is SS7 vulnerability and why is it still a threat?

SS7 (Signaling System No.7) is an old protocol that plays a key role in establishing and terminating calls, delivering text messages and enabling seamless roaming connectivity. It is still a threat because it was built based on a trust model (it lacks robust encryption) and because it is deeply embedded in legacy network systems.

How does AI improve fraud detection compared to rule-based systems?

AI improves telecom fraud detection by continuous learning loops. It can identify and flag strange patterns and adapt to them in real time. Rule-based systems rely on manual rules for triggering alarms or anomalies.