The PE was registered against "unknown persons" with an aim to ascertain as to whether the "first-come-first-serve basis" provision passed by the then Cabinet led by Atal Bihari Vajpayee was followed or not, official sources said here.
The CBI was likely to go into the minutes of the meetings held by successive Telecom Ministers which included late Pramod Mahajan, Arun Shourie and Dayanidhi Maran.
According to the sources, nearly 50 licences were given out on the first-come-first-serve basis and Bharti, Vodafone and Idea were among the beneficiaries of the policy.
The sources said that documents of the companies who have been awarded the contract would also be examined.
The Supreme Court had on December 16 directed the agency to widen its investigation to cover the grant of licences by both the NDA and the UPA regimes between 2001-2007 and submit a report by February 10 this year.
The apex court had made it clear that the emphasis of the investigation would be to determine the loss of money to the public exchequer and said a progress report on the probe has to be filed by the CBI and Enforcement Directorate in a sealed cover.
Holding that prima facie "serious irregularities" have been found in the issue of 122 licences, the court delivered a seven-point direction to the CBI and ED saying it was satisfied that allegations need a thorough and impartial investigation.
Shourie, who held the telecom portfolio between January 2003 and May 2004 in the NDA regime, had said he was not sure what made the apex court widen the scope of probe from 2001.