Public Accounts Committee (PAC) chairman Murli Manohar Joshi on Monday said the committee would probe all aspects of 2G scam. PAC is now questioning corporate lobbyist Niira Radia in connection with the alleged irregularities in the allocation of 2G spectrum. Radia's tapped phone conversations with politicians, corporates, bureaucrats, and journalists form a key part of investigations into the 2G spectrum scam. AIR correspondent quoting sources reports, the panel headed by senior BJP leader Murli Manohar Joshi is quizzing Radia on the tapped conversations which include allegations of trying to influence reported portfolio allocation to some ministers. Industrialist Ratan Tata will appear before the Parliamentary panel later in the day in connection with the case. Last week, CBI has filed its first chargesheet in the case against Former Telecom Minister A Raja and eight others. Raja is in jail for alleged irregularities in the allocation of 2G spectrum licenses. A Joint Parliamentary Committee (JPC), chaired by Congress leader P C Chacko, has also been set up to look into all the details of the 2G spectrum allocation from 1998 to 2008.