Hold the Phone! 5 Types of Voice Fraud You Should Know

On a daily basis, we experience voice fraud through spam calls when no one is on the line or if an automated voice answers back. But spam belongs in a tin, not our communications.

What seems like a nuisance to us is actually costing the telecommunications industry an estimated €29 billion a year, according to a report from Europol. With the rate of voice fraud climbing 350%+ from 2013-17, with an increase of 47% between 2016-17.

Fraud is a problem we, like all providers, are combating on our network. And as long-term proponents of compliant comms, we take fraudulent activity on our numbers seriously.

As fraud shows no signs of slowing down, we’ve listed the main types of abuse cases to look out for:

CLI Spoofing

Has a caller ever claimed you’ve phoned them before when you haven’t? Then your phone number might have been spoofed by someone else. CLI Spoofing is used to describe situations in which the motivation is considered malicious by the caller. As an example, scammers can use applications to spoof calls and manipulate phone networks to ring from a phone number that they’re not calling from.


Robocalls use a computerized auto-dialer to deliver recorded messages. These types of calls are often associated with political and telemarketing phone campaigns. In March 2019, 5.2 billion robocalls were made. That’s an average of 168.8 million per day, according to YouMail, a robocall management company that tracks call volumes.

Wangiri Fraud

Wangiri literally translates to “one (ring) and cut” in Japanese. A call will be made and then abruptly ended before you can answer, leaving a premium rate number in your missed calls. The aim of the scam is the hope that you’ll call back that number and unknowingly pay the tab. Although the majority of providers block any numbers associated with Wangiri, scammers are constantly changing up the numbers they use so it’s likely end-users will still get hit.

War Dialing

Hackers use war dialing as a way to target as many phone numbers as possible. This software can scan a list of numbers, dialing every one in a local area code to search for unprotected routers. They can then review the log for routers, go back and attempt to break into the system to which it is connected and gain access to the network.

Telecom denial-of-service (TDOS)

Telecom denial-of-service (TDoS) attacks are a type of data network denial of service (DDoS) attack, but instead target your voice systems. They require an automated phone dialer that calls a target phone number and hangs up — over and over again. That means the service is flooded with so many malicious calls that genuine callers can’t get through. This can be particularly harmful for critical phone systems like emergency services that get inundated with these types of calls.

Fraud is something that will never entirely go away, but providers can put preventative measures in place to help limit its impact. We have a dedicated abuse team, that investigates any suspected fraud cases on our numbers. They ensure that as a company we are complying to regulations, and are always available to take calls from local authorities. If there are a series of abuse cases of unwanted or nuisance calls on business allocated numbers, we will be forced to disconnect services.

If you suspect any fraud on your numbers, or want to learn more about the types of fraud listed above please get in touch.