However, Rab could not arrest anyone during the raids as the corrupt businessmen fled away sensing the presence of the elite force members.

Finding unusual gatherings, Rab-4 members raided Ahmednagar, Paikpara and Badda areas and found three offices operating such illegal business, Rab officials said.

Rab-7 members in Chittagong busted two VoIP business centres-- one on the fifth floor of Nazir Ahmed Complex at Riazuddin Bazar and another at 58, Nalpara in Kotwali.

Yesterday's raids in Chittagong were conducted after a tip-off that some people are operating VoIP equipment to illegally divert calls abroad by call origination and termination using BTTB phones and mobile SIM (subscriber identity module) cards in the areas, Rab sources said.

The seized items include huge quantity of receivers, cables, circuits and integrated circuits.

With yesterday's recovery, the Rab so far busted 12 unauthorised VoIP business centres-- nine in the capital and three in Chittagong-- since December 26 last year.

According to Rab officials, the value of the total seized items would be worth several hundred crore taka.

Illegal VoIP operators use the equipment to generate or terminate overseas calls by first turning voice calls into data, routing it over the Internet and then turning the data into voice again.

The method, also known as Internet Telephony, bypasses BTTB (Bangladesh Telegraph and Telephone Board), the sole carrier for overseas calls in Bangladesh and thus gets away without paying a huge revenue.