These 323 residential lines were in the name of BSNL General Manager connecting the Boat House residence of Maran with office of Sun TV through a dedicated underground cable during the tenure of Maran as Telecom Minister, sources in the CBI claimed.
The agency has recommended action to Telecom Secretary in 2007 but the department allegedly did not give its nod in the case, they said.
CBI has now decided to file a preliminary inquiry in the case against unknown persons, they said.
The sources said these lines were not ordinary telephone lines but more costly ISDN, capable of carrying huge data thus facilitating faster transmission of TV news and programmes across the globe.
CBI in its report to the Telecom Secretary has alleged these lines are used by medium to large commercial enterprises to meet special needs such as video conferencing, transmission of huge volume of digital data for which heavy price is to be paid but allegede that Sun TV got it for free because of Maran.
It said that this virtual exchange was programmed in such a way that except "authorised BSNL staff" no one in the state-owned telecom company was aware of its existence.
The CBI alleged that a stealth cable was used to connect the residence of the Minister with Sun TV office to give impression that these lines were for the Minister but actually they were used by the channel.