Telecom call fraud scenarios

TransNexus has recently released a new white paper, An Introduction to VoIP Fraud.

As a preview, here are a few of the fraud scenarios featured in the paper.

False Answer Supervision. When a dialed phone number is not in service, the calling party will hear a brief recording telling them so. There is no answer supervision or connection between the calling and called party. Since the call never connects, it is an incomplete call and should not be billed. However, fraudsters use false answer supervision to make these calls appear as completed calls which may be billed. Perhaps the fraudster has published rates for terminating calls without any intention of actually completing the calls. Here, service providers will route calls through the fraudster, who, instead of terminating the call, will play a not in service message and then bill the service provider for more than 10 seconds of calling. This type of fraud hurts the originating service provider both by costing money, and by hurting their reputation.

The key indicators of this type of fraud are:

  • Short phone calls
  • Calling party hangs up nearly 100% of the time
  • High answer seizure ratio

Location Routing Number (LRN) Fraud. Location Routing Number Fraud or LRN fraud works based on the desire of some service providers to avoid extra charges from LRN “dips.” Most providers will run an LRN dip to determine the correct LRN for a dialed number.

However, many service providers will not perform an LRN dip if the LRN is already in the SIP message. Fraudsters take advantage of this by inserting fake LRNs into their calls. For example, they may insert the LRN for a relatively cheap terminating destination, when the call is actually going to a high cost rural destination. The service provider will then bill the fraudster for the cheaper call, but will have to eat the cost of the expensive rural call. In some cases, this can be up to 5x the price they billed the fraudster.