An anonymous reader writes: Immigration and Customs Enforcement’s (ICE’s) Homeland Security Investigations carried out a nationwide operation between June 22 and July 10 that dismantled “SIM farms” run by transnational criminal organizations.
SIM (subscriber identity module) farms are systems containing large numbers of SIM cards from different wireless carriers, often housed in banks of cellphones, modems, or specialized devices known as SIM boxes.
These can be used to send and receive bulk messages or calls and often exploit voice over internet protocol (VoIP) technology to do so. Initially developed for legitimate purposes, the technology has become prominent among organized fraudsters targeting mass audiences through phishing texts, scam calls, and fraudulent online accounts.
The recent nationwide operation, dubbed Operation Signal Break, “dismantled critical command-and-control infrastructure used to perpetrate large-scale telecommunications fraud across the United States,” ICE said in a July 24 statement.
Authorities will now analyze the seized SIM data to identify victims and assess losses caused by such fraud. The illicit proceeds from the fraud, which are suspected to be linked to Chinese transnational criminal organizations and distribution networks, will be traced.
This is expected to support criminal indictments, sanctions targeting national and international infrastructure used in criminal activity, and asset seizures. SIM box operations are estimated to result in losses worth $15 million annually to Americans, according to ICE.
SIM box fraud, “also known as interconnect bypass fraud, is a scheme in which fraudsters reroute international calls to appear as local ones,” a Nov. 8, 2025, post from IT services provider Synaptique said.
For instance, when a foreign national calls someone in the United States, the call is diverted through VOIP to a SIM box in America instead of passing through a legitimate international call gateway. The SIM box then uses one of the local SIM cards to place a new local call to the recipient.
