IRSF fraud
IRSF — International Revenue Share Fraud.
IRSF is one of the most expensive forms of telecom fraud. Attackers hijack a PBX, SIP account or switch and pump calls to premium international numbers they profit from — leaving someone else with the bill, often within hours.
The scheme
How IRSF works
A fraudster obtains numbers in premium-rate or high-cost international ranges from a provider willing to share the termination revenue. They then gain access to a phone system — usually through weak SIP credentials, an exposed PBX or a compromised customer account — and generate as many calls to those numbers as possible.
Attacks are typically timed for nights, weekends and holidays when nobody is watching. By the time anyone notices, the losses can run to tens of thousands of dollars, and because the terminating carriers involved appear legitimate on paper, recovering the money afterwards is very difficult.
Why IRSF is hard to stop
Fast onset
Attacks ramp to full volume in minutes and can do serious damage before a morning report ever runs.
Rotating destinations
Abused number ranges change constantly, so static blocklists go stale quickly.
Little recourse
Once minutes are terminated, disputing the charges across multiple international carriers rarely succeeds.
How VoIP Radar blocks IRSF
VoIP Radar scores each outbound call against continuously updated intelligence on high-risk international ranges and a behavioral baseline for every customer and extension. Sudden spikes to risky destinations, unusual hours or new countries are throttled or blocked in the same second they begin — not the next morning.
Spend and minute thresholds can automatically suspend an account mid-attack, and your NOC receives an alert with the evidence to act on.
Get in touch
Find out where your network stands
Tell us about your switch and traffic. A VoIP Radar engineer will map your STIR/SHAKEN, RMD and fraud exposure and send a written assessment — free, within one business day.
- STIR/SHAKEN & attestation review
- RMD certification gap check
- Fraud & robocall exposure snapshot
- Deployment plan for your SBC / softswitch