According to the Communications Fraud Control Association, telcos and consumers have lost over $38 billion to phone fraudsters over the last decade. The most lucrative scam, accounting for $4 – $6 billion in damages, has been International Revenue Share Fraud (IRSF).
IRSF takes advantage of premium phone numbers that charge callers a certain fee in exchange for a certain service to the caller. Premium numbers are offered by International Premium Rate Number (IPRN) providers, that charge telcos and customers based on the number of calls they receive. Many IPRNs cooperate with cybercriminals who use illegitimate tactics to redirect traffic to IPRN networks.