Here's the fascinating way presidential phone calls get made - and how Trump has already disrupted the norm
US President-elect Donald Trump spoke with the president of Taiwan over the phone Friday, a diplomatic move that seems to have broken many rules about how phone calls between world leaders get made.
Though Trump is a highly unusual president-elect - having never held elected office - there's a normal procedure in place for these types of phone calls since Rutherford B. Hayes first installed a telephone in the White House in 1877. Everything is meticulously planned to leave very little to chance.
When President Barack Obama calls other world leaders, for instance, his aides bring him a National Security Council dossier that contains a complete intelligence portrait of the person with whom he's about to get on the phone. The dossier includes everything from the leader's personality and health to information about their children and spouses - even tidbits like whether the person likes jokes or small talk, Yahoo News reported in 2014.
"The world leader profiles include basic intel, idiosyncrasies, personal political pressures, whether any close relatives are seriously ill, girl- or boyfriend problems, personal health issues," a senior administration official told Yahoo News at the time.
Immediately following the call, officials from both sides will produce "readouts," or short summaries designed to drive media coverage.
Trump's call on Friday was directly at odds with Washington's "one China" policy - in place since 1979 - which maintains that Taiwan, though self-governing, is a province of the Chinese communist government based in Beijing. The White House was not aware of the call until after it occurred, an administration official told Business Insider.
And Trump has made a few other calls since winning the presidency that have been at some odds with previous US policy. Pakistan, for instance, said its leader invited Trump to visit the country during a chat with Trump, a move that could potentially alienate India. And Trump also spoke with the leader of Kazakhstan, who has been a strongman-type ruler over the country.
Yet it seems unlikely in the immediate aftermath that Friday's Trump call will permanently affect US-China relations, as China's foreign minister, Wang Yi, referred to the call a "small trick" by Taiwanese officials.
And, as Yahoo reported, these calls can get a whole lot messier. President George W. Bush often had the most difficult time on calls with Hu Jintao, the former Chinese leader.
"They were unbelievable. Almost all of them were more than an hour long," a former administration official told Yahoo News. "Every call to a Chinese president had to start with a restatement of America's Chinese policy."
Bush was forced to reiterate the US's policy towards China - the same policy that Trump (perhaps unknowingly) flouted on Friday:
"The United States maintains our one China policy based on the three communiqués and the Taiwan Relations Act. We oppose unilateral changes in the status quo in the Taiwan Strait by either side, and we urge all parties to avoid confrontational or provocative acts. And we believe the future of Taiwan should be resolved peacefully."
"It was talking points, talking points, talking points ... and then in the last 10 minutes you'd get to the point," the official told Yahoo News. After the call, officials on both the US and Chinese side would race to get their readouts out to the media.
Obama, for his part, definitely preferred speaking with some foreign leaders over others.
Officials said Obama's calls with Russian President Vladimir Putin were often "grueling," according to Yahoo, and he once spent 90 minutes on the phone - his longest phone call with another world leader - trying to convince Putin to pull his troops out of the Crimean peninsula.
Obama much preferred speaking with Dmitry Medvedev, the former Russian president, with whom he apparently "really got along." Former Egyptian President Mohammed Morsi was "always really friendly and conversational," administration officials told Yahoo News.
While the Cold War era "red telephone" between Washington and Moscow was only found in Hollywood, the first thing you hear when you're about to speak to the president is like something straight out of the movies.
"Please hold for the president," a national security staffer would say, right before Obama - and, after January 20, Trump - takes the call.