Was Trump's Taiwan contact a policy shift or a misstep?

Was President-elect Donald Trump signaling a shift in US-China relations when he referred to Taiwan's leader as "president" following a phone call this past week or was it an unintentional misstep?
His phone conversation with Tsai Ing-wen was a breach of long-standing tradition that risks enmity from China, but a longtime China watcher says he can't yet be sure of the meaning.
Douglas Paal, a former director of the American Institute in Taiwan, which unofficially represents US interests in Taipei, said it was too soon to judge whether Trump was going to lead that shift, or if the incident was just a "complicated accident."

"Beijing will watch closely to see which it is," said Paal, now vice president for studies at the Carnegie Endowment for International Peace. "But until someone from Trump Tower explains further, it is unknowable."
The US shifted diplomatic recognition to China from Taiwan in 1979.
But the governments in Washington and Taipei have maintained close unofficial ties and deep economic and defense relations.

The US is required by law to provide Taiwan with weapons to maintain its defense, and since 2009, the Obama administration has approved USD 14 billion in arms sales to Taiwan.
Trump's conversation with Tsai drew an irritated, although understated, response from China, as Foreign Minister Wang Yi said yesterday that the contact was "just a small trick by Taiwan" that he believed would not change US policy toward China, according to Hong Kong's Phoenix TV.

"The one-China policy is the cornerstone of the healthy development of China-U.S. Relations and we hope this political foundation will not be interfered with or damaged," Wang was quoted as saying.
Chinese officials said they lodged a complaint with the US and reiterated a commitment to seeking "reunification" with the island, which they consider a renegade province.
The call was the starkest example yet of how Trump has flouted diplomatic conventions since he won the November 8 election.
He has apparently undertaken calls with foreign leaders without guidance customarily given by the State Department, which oversees U.S. Diplomacy.
"President-elect Trump is just shooting from the hip, trying to take phone calls of congratulatory messages from leaders around the world without consideration for the implications," said Bonnie Glaser, senior adviser for Asia at the Center for Strategic and International Studies in Washington.