The Mumbai Police on Thursday busted illegal VOIP exchanges that were used to call defence persons seeking information related to key military installations.

The raid was carried out in a joint operation with military intelligence.

Two functional sim boxes were recovered with 100 slots each along with 200 SIM cards, two routers, three modems, antennas, batteries and connectors. The equipment was recovered from Uttar Pradesh's Noida and Changaramukulam in Kerala. One person was also arrested from Changermakulam, Kerala. The devies are now being investigated.

In September last year, defence persons received calls from suspicious numbers, seeking information related to important defence installations. The callers posed fictitious identity.

Upon investigation, it was revealed that there are a few illegal VoIP exchanges at Noida and Kerala, which route calls incoming from Pakistan to local numbers. The calls were then used to extract information from defence persons. Based on this information, Mumbai Police launched joint operation with military intelligence.

Probe is underway to ascertain identity of more individuals who are involved and locations of other similar exchanges. More arrests are likely to be made in this connection in the near future, as they might also be linked to compromising the country’s internal security.

The recovered VOIP exchanges converted international voice calls originating from Pakistan into local GSM calls using the Chinese SIM Boxes (boxes fitted with GSM SIM cards of local cellular service providers). These SIM boxes use a dynamic IMEI system, which makes them difficult to be tracked. This system has already been declared illegal by Telecom Regulatory Authority of India.

Since Indian systems cannot control the calls generated in such systems, they are also used for anti-national activities. Therefore, the Department of Telecommunications is not permitted to transmit international VoIP calls through the normal telephone network. The SIMBOX methodology is a financial fraud to the Government of India as well as to mobile companies.

Investigations so far have revealed that the busted exchanges caused revenue losses in crores to the telecom department. Subsequent probe further told that those exchanges were being used by hostile intelligence agencies to seek military information through calls and posed security threat to nation.

After the preliminary inquiry and the confirmation of the usage of unauthorized simboxes, a case has been registered under section 419, 420, 465, 468, 471, 120 (b) of IPC with the clause 1 of Indian Telegraph Act 1885, Sections 4, 20, 25, with section 3, 6 Indian Wireless Telegraphy Act 1933, & forwarded the investigation to the crime branch.