Bhubaneswar, July 8: Mumbai police arrested four persons from Ganjam district today over suspected links with underworld don Chhota Rajan.

Five China-made SIM boxes were seized from them their possession.

This is said to be the first exposure of a cyber crime racket, which was executed using SIM boxes or smaller version of telephone exchanges, which can divert international calls to local calls to avoid police scrutiny.

The use of SIM boxes for international calls violates the Telecom Regulatory Authority of India (TRAI) guidelines. It also causes loss to the exchequer as international calls get converted to local calls.

The four arrested persons include the mastermind, identified as Pradeep Choudhury, who was operating the SIM boxes.

Berhampur additional superintendent of police Trinath Patel said: "A dreaded gangster from Hong Kong and a close associate of Chhota Rajan, Suresh Pujari, had demanded Rs 2 crore as ransom from a Mumbai-based realtor over the phone.

After tracing the call, the Mumbai crime branch found that the call was made from Berhampur.

Subsequently, they contacted the local police who raided various places and arrested three persons from Berhampur and one from Chhatrapur. Patel said the investigation revealed that the calls were made through the SIM boxes.

"Pujari called from Hong Kong via a SIM box (in Berhampur) which diverted the call to Mumbai as a local call. It is difficult to trace such call as it camouflages the caller's identity. Such acts come under cyber crime and it is a new kind of crime in Odisha," he said.

Hinting that the local police may have to go abroad for further investigation into the case, Patel said: "The Mumbai crime branch is in constant touch with us. Future course of action will be decided after discussion with our senior officers."