IRSF (International Revenue Share Fraud)

International Revenue Share Fraud exploits the legitimate system by which telephone carriers pay each other for completing calls. An operator in a particular country can negotiate a revenue-share agreement with a carrier in another territory, then fraudulently generate large volumes of calls to numbers under their control. The originating carrier — often a business whose PBX or SIP trunk was compromised — receives a huge bill while the fraudster pockets the termination revenue before disappearing.

IRSF losses are estimated in the billions of dollars annually and are a leading category of telecom fraud worldwide. Attackers typically gain access to corporate phone systems through brute-forced VoIP credentials, compromised routers, or stolen SIM cards, then route traffic overnight when activity is unlikely to be noticed. Small and medium businesses are common victims because they often lack real-time call monitoring.

For consumers, IRSF most commonly surfaces as an unexplained spike in phone bills, especially after a SIM swap or device compromise. Businesses should enable real-time fraud detection on their VoIP platforms and set hard call-spend limits per period.