Call Stretching & Short Stopping Fraud – Protecting Operators in Premium Rate Destinations

Tuesday 7 Jun 2022 | Member Press Release | Member Resources |

In 2021, fraud-caused losses to telcos around the world totaled close to $40 billion, while global telecom revenue lost specifically to Short Stopping and Call Stretching attacks was estimated at $4 billion

But these fraud schemes don’t just steal revenue – they cause customer churn, create unresolvable disputes and lead to the blockage of entire numbering plans from specific countries. People are unable to reach their family and friends in such destinations and, as a result, the terminating operators in these regions lose revenue due to lost traffic.

Due to the strategies used by these fraudsters, operators in destinations with high termination rates – such as the Maldives, Algeria, or the EU – are particularly at risk. But in contrast with spam calls, the industry has seen little response from regulators. 

At a time when Call Stretching and Short Stopping attacks are on the rise, the chances of preventing them are becoming smaller and smaller. Thankfully, call validation can put an end to this issue, once and for all.

But to understand how we can stop these fraud schemes, it’s vital to first understand how these particular fraud schemes operate.

What are Call Stretching and Short Stopping?

To understand these fraud schemes, let’s consider an example of a normal, non-hijacked call process. Imagine a call that originates in Canada and terminates in Cuba. The Cuban operator (B Operator) eventually charges $5.00 for the 10-minute call. 

In a legitimate call, several wholesale transit carriers each collect, for example, one cent per minute for connecting the call.

Each carrier charges the next carrier in the routing chain until the A Operator pays the full amount for the total duration of the call. 

Call Stretching vs Legitimate Call

Call Stretching occurs after a call has been connected for some time. For example, at the five-minute mark, a fraudulent carrier disconnects the B-side and connects the A-side to a recording of the conversion (or some other recording to keep the A-side connected for as long as possible) to extend the charged duration of the call and directly funnel the profits into their pocket. 

In some cases, a recording may ask the caller to remain on hold while the called party is away – anything to prolong the call.

In the above example, the fraudulent carrier charges the preceding carrier $0.50 /min for every second or minute the A-side stays connected after the five-minute mark and collects the profits. And at the same time, neither the A nor B operator is aware the call has been disconnected and fraudulently prolonged.

Short Stopping vs Legitimate Call

Short Stopping is based on the same principle, but the hijacking occurs before the call connects to the intended destination, usually by a fraudulent transit carrier in the transit path. 

The call is rerouted to a high rate destination with a live answer or connected to a recording. Again, the goal is the same – to keep the caller on the line for as long as possible and rack up charges.

Sometimes, the caller will hear a typical disconnection notice or the fraudster will pay a message such as, “Hello? Hello? I’m having trouble hearing you. Please hold on…” etc. 

Since these recordings often sound real, callers may not even be aware the fraud has occurred until they get an enormous bill for calls to a destination they never dialed.

The common thread between the two schemes is the exploitation of premium rate destinations. This poses a threat both for terminating operators and ordinary people trying to get in touch with friends and family in these destinations.

Targets of Call Stretching and Short Stopping: Premium rate destinations

Below is an incomprehensive list of high rate destinations targeted by Call Stretching and Short Stopping:

  • Falkland Islands (€1.17/min)
  • Seychelles (€0.48/min)
  • Cuba (€0.50/min)
  • Chad (€0.42/min)
  • Maldives (€0.62/min)
  • Tunisia (€0.59/min)
  • Algeria (€0.61/min)
  • European Union (€0.13 – €0.40/min)

The lack of a reliable and accurate way of stopping fraud attacks has prompted many operators to take the desperate measure of blocking the entire numbering plans of such countries. As a result, local operators in these destinations lose immense traffic volumes and the corresponding revenue. And many callers simply can’t reach people by phone in these countries. 

Consequences of Call Stretching and Short Stopping 

These attacks harm end-users, originating telcos, terminating telcos, and entire countries.

End-users face:

  • enormous charges on their phone bill to countries they never dialed
  • privacy violations as their conversations are recorded
  • being blocked from calling the entire numbering plan of certain countries and regions

Originating telcos suffer from:

  • financial losses from the fraud itself
  • payment disputes and trouble ticketing
  • customer dissatisfaction and immense churn

Terminating telcos suffer from:

  • shorter call durations & calls being rerouted to other destinations 
  • loss of international traffic from country-wide blockages
  • loss of corresponding revenue

Preventing Call Stretching and Short Stopping

So, why do traditional fraud management systems struggle to detect and stop these fraud schemes? 

In short, these systems monitor for widespread patterns in a massive amount of calls and other substantial indicators of International Revenue Share Fraud. These traditional FMSs are trained to detect:

  • unusual call volumes to uncommon destinations 
  • lower answer-seizure ratios (ASR) 
  • large volumes of simultaneous calls to and from certain ranges

And more. 

But as we discussed, in Call Stretching and Short Stopping the initial call is entirely legitimate – it’s the ending that’s incriminated. The fraud is hidden in legitimate calls, making it difficult for a traditional FMS to detect it.

The issue is further complicated by the lack of transparency in the transit space of the call chain. Fraudulent transit carriers are mostly free to do what they want with a call – reroute, cut, stretch, etc. – without being detected. 

Our ability to immediately detect and prevent such fraud schemes depends on our ability to address the above-mentioned issues, especially the lack of transparency in the transit path.

Interestingly, the call details of the A and B call registries offer the opportunity to do just that. 

Eliminating Call Stretching Via the Cross-Validation of Call Details

The solution is to provide operators with a lean, out-of-band network link to communicate information regarding the events of the call chain. More specifically, to cross-validate the call details from the A and B registries in real-time. 

This eliminates all of the above-mentioned issues and allows operators to stop 100% of all fraudulent calls before they connect.

This is the basis on which the AB Handshake solution operates. 

Preventing Call Stretching and Short Stopping – AB Handshake Solution

The AB Handshake solution can detect and prevent all Call Stretching and Short Stopping attacks on a network before calls connect.

Here’s how it works:

  1. When a call is initiated, the originating operator sends relevant call details to Call Registry A. These include the A and B numbers and time-stamps for the start, connection, and end of the call.
  2. The terminating operator sends their respective call details to Call Registry B.
  3. The call registries simultaneously exchange encrypted messages via the internet to cross-validate the call details.

The slightest discrepancy can mean only one thing – fraud. The call is signaled as fraudulent and the operator can choose to either block it or allow it to connect. 

The traffic of any operator equipped with the AB Handshake solution is guaranteed to be 100% free from all Call Stretching and Short Stopping attacks as well as all other voice fraud. It also guarantees zero false positives, which is a key issue in fraud prevention.

As more and more operators join the fraud-free community, the volume of fraud-free traffic grows as the volume of vulnerable traffic shrinks, eventually leaving fraudsters with nowhere to turn. If adopted on a global scale, AB Handshake can eliminate Call Stretching and Short Stopping (and all voice fraud) worldwide.

Integrating the AB Handshake Solution

The team behind AB Handshake realizes that such a vision can only be achieved if the solution is affordable and compatible with the native system of any operator in any location around the world.

The AB Handshake solution requires no upfront CAPEX and can be easily integrated into the default settings of any operator’s existing system. Additionally, it can work alongside any operator’s current fraud management software.

Thanks to the pay-as-you-grow model, operators of any size can adopt the system at a rate that suits their budget and fits within the cost structure of the local market.

Stop 100% of Call Stretching and Short Stopping Attacks With AB Handshake

By eliminating Call Stretching and Short Stopping, operators in premium rate countries and regions can recover billions of dollars in lost revenue annually. Yet, the benefits of eliminating these fraud schemes reach far beyond financial recovery. 

Transparency along the entire call chain facilitates more effective dispute resolution. A higher degree of security leads to a better customer experience, increased brand loyalty, and decreased customer churn. Fraud prevention methods that rely on outdated, ineffective, and costly methods, such as country-wide blockages, can finally be abandoned. And that’s only the beginning.

AB Handshake already monitors live traffic in every country around the world. The solution currently validates the traffic of more than 200 operators worldwide and we are actively branching out. 

If you would like to learn more details or want to join the AB Handshake community on the spot, please get in touch with us

Disclaimer: The views and opinions expressed in this article/press release are those of the authors and do not necessarily reflect the approved policy or position of the GSMA or its subsidiaries.