Confronting the Flash Call Conundrum: Detection, Monetization, and Real-Time Solutions for Mobile Operators

Within recent years, flash calling has become a hot industry topic. This one-time password (OTP) or two-factor authentication (2FA) method involves triggering a missed voice call or over-the-top (OTT) call to subscribers, eliminating the need for a traditional application-to-person (A2P) SMS containing the OTP message. While flash calls offer cost-effective OTP delivery with improved customer experience, Mobile Network Operators end up suffering from a direct monetary loss due to decreased A2P SMS revenues.

Is it fraud?

Since flash calls are zero duration unbillable events, it’s common for operators to be left in the dark unaware if flash calls are even occurring on their network. In addition to the lack of visibility, many countries have not yet implemented any laws or regulations prohibiting telephony services from making zero-duration flash calls for OTP delivery. This leaves it up to the operators to decide if they will update their terms of service to define flash calls as a violation, start charging for flash calls, or do nothing as they watch their A2P revenues decline. Outside of the latter, Operators need an effective method to detect flash call occurrences so they are equipped with the necessary information to make an informed decision on how they will handle incoming flash calls.

Test Call Generation (TCG)

To easily assess the potential threat of flash calls on the network, an A2P TCG campaign can be leveraged. This low-cost testing approach is quick to deploy (less than one week setup time) and provides insights into the percentage of OTP requests made by network subscribers that result in traditional A2P SMS vs flash call events. This approach is a helpful first step for Operators in their journey to understand and manage flash calls to their network. TCG insights  empower them to understand the potential threat on hand. However, Operators should be aware that TCG alone provides a limited insight into the overall impact of incoming flash calls to the network. While it is a helpful preliminary testing tool, it should not be considered a comprehensive detection, prevention, or control method alone for flash calls.

Like most telecom fraud scenarios, a multi-layered approach is recommended to protect the affected network that offers both comprehensive detection and prevention. With LATRO, this is accomplished through a combination of TCG and implementation of a Real-Time Verification System through our Versablocker platform.

Real-Time Verification Systems

By design, automatic routing of incoming calls to the mobile operator’s core network is enabled by the Session Border Controller (SBC) and Gateway MSC (GWMSC). This is essential to support seamless connection of incoming calls while effectively load balancing with available network resources. The downside of this design is that fraudulent or unwanted calls are automatically routed into the network without any filtration checks. To circumvent this, Real-Time Verification Systems, like Versablocker, can be integrated with the network using Camel/SIP or Diameter protocol as a control point trigger before the SBC/GWMSC sends calls to the core network. When implemented, the system supports:

  • CDR generation of flash calls

Versablocker generates special CDRs for the non-billable zero duration calls that are not tracked in any existing network support systems. These CDRs provide visibility into the otherwise unknown flash call events.

  • Monetization of flash calls

Versablocker can generate CDRs for flash call events. Flash call CDRs can be integrated with mediation as a reliable source of new information for the Wholesale team to monetize the service as an additional revenue stream.

  • Detection of flash calls

Versablocker includes a full toolbox of verification and analysis functionalities that allow for advanced rule profiling to detect flash call occurrences. This can be used in conjunction with TCG detections or as a replacement detection method.

  • Real-time blocking of flash calls

All incoming calls can be checked against a blocking list, numbering plan, external databases, and/or live threshold rules to determine if the call should be accepted into the core network. This helps protect the network and reject any incoming flash calls if desired.


Despite the rapid rise of flash calls since 2021 and continued growth projections, many operators have not yet formed strategies for managing such events. Fortunately, operators don’t need to make costly decisions without supporting data. Prior to investing in sophisticated technical solutions, operators can harness simple yet highly efficient tools like TCG to evaluate the potential cost of the problem. This information can then serve as the foundation for a well-considered strategy for addressing flash calls encompassing detection, monetization, and/or blocking.

LATRO’s team of experts will help you identify which strategy best aligns with your business needs. Drawing upon our extensive experience in assisting global operators grappling with similar challenges, we can offer invaluable insights. If it is determined that a comprehensive flash call solution is the ideal fit for your business, LATRO’s Versablocker, as a Real-Time Verification System, stands ready to provide you with the support you need.

Contact us today to find out more about LATRO solutions, request a demo or connect with us via the contact form.