They had stayed away from the subsequent two proceedings of the Committee.
Before attending Thursday's proceedings, BJP members had said the deposition of former cabinet secretary KM Chandrasekar has given ample evidence to call the Prime Minister and the finance minister before the panel.
Chacko has ruled out calling the Prime Minister and has said there is no consensus in the committee to call Chidambaram as a witness.
A body of GSM operators is appearing before the JPC on Thursday to put across the views of the telecom operators before it finalises its report.
BJP has six members in the JPC including Yashwant Sinha, Jaswant Singh, Dharmendra Pradhan, Gopinath Munde, Haren Pathak and Ravi Shankar Prasad.