CNN reports that President Donald Trump's started handing out his personal cell phone number to world leaders shortly after he took office last year.
According to a report in The Washington Post, this has led to one-on-one calls that even top White House aides did not know about.
According to the Post, White House aides learned of an April 2017 call between Canadian Prime Minister Justin Trudeau and Trump only after a standard summary was issued by officials in Canada.
The Post said its report was based on interviews with US and European officials who spoke on condition of anonymity.
The Post reports that conversations with world leaders are required by Federal Records law to be routed through the Situation Room.
Such calls are typically heavily prepared for and monitored by the White House, the National Security Advisor briefs the president and regional experts provide prepared talking points.
The National Security Advisor then remains by the president's side throughout the call.
A transcript of the call has been distributed to the key White House aides who issue a public readout.