How to prevent Telephony Denial of Service (TDoS) attacks

We’ve noticed an uptick in inquiries about solutions to prevent TDoS (Telephony Denial of Service) attacks. Such attacks are bad news: they can target and overwhelm critical telephone systems, such as emergency response numbers or call centers. The good news: effective solutions are available.

TDoS attack profiles

There are different versions of TDoS attacks. They share a common feature in generating many calls to a destination, which eventually overwhelms the PBx or trunk. They vary in how these calls are generated.

Centralized TDoS attack

Centralized TDoS attack

In a centralized TDoS attack, computer software is used to generate many calls from one source.

Distributed TDoS attack

Decentralized TDoS attack

With a distributed TDoS attack, malware is distributed to many call sources to programmatically generate lots of calls at the same time.

TDoS prevention

With either profile, attacks can be prevented by analyzing call traffic. When the volume of traffic breaches a threshold, further calls are blocked or diverted, ending the attack.

In a centralized attack, the fraud prevention software scores telephone calls with common attributes, such as calling and called numbers, users and groups. When the cumulative score for a commmon grouping breaches a threshold, further calls are blocked or diverted to IVR for a period of time. The attack is ended.

With a distributed attack, fraud prevention software scores call traffic to a destination. When the cumulative score of calls to a given number crosses a threshold, further calls to that destination are diverted to an Interactive Voice Response (IVR) system for screening. The IVR prompts the caller for a response, which the distributed malware cannot provide. The attack is over.

TransNexus TDoS prevention solutions

We offer services with our NexOSS and ClearIP software products to prevent TDoS attacks:

  • SIP Analytics analyzes call traffic for detection of TDoS attacks, fraud attacks and unwanted robocalls. Once detected, calls can be blocked or diverted.
  • CAPTCHA gateway is an IVR system that accepts diverted calls and prompts for human interaction.

We offer these services on-premises or in the cloud, providing scalability to defeat any TDoS attack.

Contact us today for more information on TDoS prevention.

Request info about our products and services

* required

This information will only be used to respond to your inquiry. Transnexus will not share your data with any third parties. We will retain your information for as long as needed to retain a record of your inquiry. For more information about how we use personal data, please see our privacy statement.

More on TransNexus.com

July 10, 2019

July holiday week telecom fraud attack profiles

June 13, 2019

ClearIP enhancements for blacklisting of SPID and location

May 20, 2019

Anatomy of a telecom fraud attack

May 14, 2019

Study on rule changes to eliminate access arbitrage

May 8, 2019

FCC warns of Wangiri telecom fraud scams

March 14, 2019

How to prevent Telephony Denial of Service (TDoS) attacks

March 8, 2019

SIP Analytics vs. CDR-based fraud management – a case study

October 22, 2018

FCC proposal to curb domestic telecom fraud

September 27, 2018

Lessons learned from call forwarding attacks

September 10, 2018

Prevent telecom fraud with blacklist call forwarding