During a 20-minute call from Frankfurt where he made a overnight halt on his way to New York, Singh discussed with Chidambaram the issue of a 10-page note sent to the Prime Minister's Office(PMO) by the Finance Ministry in March last.
The note that became public after the Prime Minister had left Delhi on his foreign tour suggested that the scam could have been avoided if the Finance Ministry, then under Chidambaram, had insisted on spectrum allocation through auction. The Minister has since been under attack.
The Prime Minister is believed to have counselled Chidambaram "to be patient" till he returns home from New York on September 27, highly placed sources said.
The sources also said that the Prime Minister was ready to say about the Home Minister's integrity.