Either this is complete fiction or somebody is leaking intelligence intercepts. Either way, it is alleged there is a leak, so it’s pretty simple: the President should direct Comey to investigate whether than has been a leak. The only way to stop leaks is to prosecute the leakers.
Don’t see what the issue is anyway. So what if he talked to the Russian ambassador about the sanctions? He was the NSA designee named by he President Elect. Seems a bug non-issue. Intel guys shade the truth all the time.
I heard Chris Wallace on Fox say that the FBI had a transcript of the conversation.
As for other leaks, it’s someone in the White House Communications Agency. They set up the calls and hear all that is said. They probably have capability to tape also, for transcript purposes.