The idea that accepting a phone call could rustle international jimmies seems really petty, but I guess that's diplomacy.
People keep saying that and I'm a bit baffled by it to be honest. P(E)OTUS ain't exactly getting random casual calls like most of us. And it's not just that he spoke with Taiwanese authorities, but that it is publicized (on his twitter now, even) instead of speaking through confidential back-channels. All of this is incredibly deliberate and they are policy signals. President-elect Trump is waving a red flag under the nose of the People's Republic of China and he knows it.
Now I guess it's a intellectually defensible position to be more antagonistic of the PRC or that the support to Taiwan be more outspoken. Trump is being incredibly rash and reckless in how he does all this, however.
Can't help but think the Taiwan call is a deliberate signal that Trump plans on dismantling Obama's attempt to "pivot" to Asia and strengthen relations in the region. Say what you will about TPP but overall the strategy seemed pretty sound, if you want to open up Asian markets and weaken Chinese influence
Meh. He didn't have anything else to do for that than to let TPP die (which he will, it seems). Otherwise he's not, so far, going against the grain of the broad strokes of US foreign policy on the military / defense side : Trying to win back the Filipinos, met with Japan's PM, eased the fear of South Korea and pledged to defend them, being supportive of Taiwan, considering Pakistan as an ally, containing China. He's just
much more aggressive in doing so.
EDIT : I suspect Trump is playing a maximalist hand to bluff and extract as much out of international relations as he can, at least in Asia. In Europe so far the moves seems to point to seeking closer pragmatic with Russia while propping up far right populists -as Moscow does-. Trump never cared for NATO and probably for the EU and I would not be surprised he thought it is most profitable for the US to have more European partners attached each though bilateral agreements.