SIM Box (GSM Gateway)

Also known as: GSM Gateway, SIMbox

A SIM box is a device holding many mobile SIMs that terminates international voice traffic as if it were on-net local calls. Fraudsters route international minutes over VoIP into the SIM box, which then dials the destination subscriber from a local SIM, capturing the price gap between international termination and local retail tariffs. Operators detect SIM boxes through calling pattern analysis, test call generation and velocity checks.

Categories: Identity and SubscriberFraudInternet and Routing

SIM Box in context

Subscriber identifiers (IMSI, SUPI, MSISDN, IMEI) anchor authentication, charging and lawful interception. Any protocol that leaks a permanent identifier is treated as a privacy defect, which is why 5G introduced SUCI concealment on the air interface.

Telecom fraud costs operators an estimated $40+ billion per year. Common vectors include IRSF, Wangiri callback scams, SIM box bypass, PBX hacking and A2P grey routing.

To place SIM Box in the wider telecom-security picture, review DSL, Interconnect Bypass Fraud, OTT Bypass, Bypass Fraud, Traffic Pumping and Toll Fraud: each entry cross-references back to this page so you can walk the topic in either direction.

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