A Bengal police special task force (STF), investigating a simbox-based communication racket across the state, have arrested two more persons including a Bangladeshi national for their suspected involvement.

Arrested Shah Alam Talukdar is from Dhaka. The other arrested, Aftar Ali Khan, is from Odisha. Both have been brought to Calcutta for interrogations.

The first arrest was also of a Bangladeshi national, Mamun, on September 2. Another person from Nadia was arrested on September 3.

A simbox works as a virtual telephone exchange that routes international phone calls as local calls, which are charged by local mobile service providers. Simboxes, also known as simbanks, are usually fitted with a few hundred GSM SIM cards used to route calls through data-functional devices.

Sleuths on this case had expressed serious concern that such illegal exchanges could serve as “secret channels” and could threaten national security while potentially robbing network providers of rightful revenue.

This is the second time within a year that a simbox racket has been busted in Bengal. In December last year, city police busted a similar racket after receiving inputs from the Lucknow-based Military Intelligence Unit.