Hyderabad: Cybercrime networks linked to China and operating from the Golden Triangle have adopted SIM box technology to bypass telecom safeguards, enabling calls from overseas to appear as if made within India. The method allowed scams to reach victims even when their mobile data was switched off. Camps run by these syndicates in Myanmar, Cambodia and Laos have now turned SIM box fraud into a key operation, investigators said.
The deception works by making international calls seem like domestic ones, misleading recipients into answering without suspicion. Police in Jannaram, Mancherial district, recently arrested a gang using this method. During questioning, they uncovered connections to Cambodia and learnt that the calls were being routed from there.
According to officials, the criminals used Voice over Internet Protocol (VoIP) to convert international calls into local calls. Instead of passing through licensed international long-distance operator (ILDO) networks, the calls were channelled through routers connected to SIM boxes. This avoided regulatory detection and ensured that only local call charges applied, inflicting major revenue losses on telecom service providers.
The syndicates sourced SIM cards from Nagaland, Assam, Manipur and other northeastern states. These were supplied to agents across the country who operated the SIM boxes. Each SIM box could connect a minimum of 16 SIM cards and a maximum of 1,024, allowing an equal number of calls to be placed at once. In practical terms, a single device could connect 1,024 calls simultaneously. Messages could also be sent in bulk. Calls from the Golden Triangle camps were first made overseas, then routed to the Indian SIM box setups, where they were converted into local calls before reaching victims’ phones.
Golden Triangle SIM box networks exploit mobile data loophole
Officials noted that this technology could connect calls even if a recipient’s mobile data was switched off — a feature the Chinese syndicates exploited for cyber fraud. The investigation confirmed that such calls often bypassed normal display information. In many cases, victims’ phone screens showed ‘no number’ for these calls.
Authorities advised the public to treat calls from unknown numbers with a +91 prefix or calls where the number was not displayed as potential fraud, particularly if bank account details were requested. Victims or suspicious call recipients can report the matter through the Department of Telecommunications’ [https://sancharsaathi.gov.in](https://sancharsaathi.gov.in) portal, or by calling 1963 or 1800110420.
As of the latest data, the Sanchar Saathi portal has received 20,323 complaints from the Telugu-speaking states regarding such incidents. Officials emphasised the urgency of public awareness, as the scale of SIM box operations and the international backing behind them pose a significant threat to India’s telecom security.