Wholesale glossary
SIM box fraud terminates international calls through banks of local SIM cards in GSM gateways, re-originating them as cheap local on-net calls. The called operator loses the international termination rate; the fraudster pockets the spread between international and local settlement.
Why it matters
It is the classical, mechanical era of bypass fraud. Its physical footprint, SIM inventory and gateway hardware, makes it the most detectable flavour, and the discipline of catching it is mature: signalling analysis, test calls and per-SIM behaviour scoring.
What practitioners watch
Signatures: many simultaneous calls from few numbers, SIMs that never sleep, uniform call durations, rotation patterns no subscriber produces, and roamers that never move from one fixed location.
Related: Fraud Prevention · OTT Bypass Observatory · Grey Route