Definition
International revenue share fraud (IRSF) generates calls or messages to high-cost international number ranges controlled by the fraudster, who receives part of the termination revenue, while the business or subscriber that originated the traffic pays the bill.
The fraudster obtains number ranges, often in destinations with high termination rates, through a party willing to share revenue. They then drive traffic to them: by hacking a PBX or SIP account and placing calls, by abusing roaming SIMs, or by triggering a business's automated voice or SMS services.
Verification flows are a common entry point. A voice OTP or flash call to a premium range can cost far more than an SMS, so a bot that requests thousands of calls creates a large bill quickly. The SMS variant overlaps with SMS pumping (artificial inflation of traffic).
Prevention: restrict outbound calling and messaging to the countries you actually serve; rate-limit verification requests per number, IP and device; set spending caps and alerts per destination; secure SIP credentials with strong passwords, IP allowlists and encryption; and review call detail records for unusual destinations or durations, especially at night and weekends.
Fraud often happens outside office hours, so automated thresholds that block traffic matter more than manual reviews.