I'm inclined to agree that this was not simply a 'misunderstanding' - if it was, then why did the Taiwanese take photos of their president on the phone with Trump and immediately post them on the internet? Given that Taiwan and the US have not had formal contact since ca. 1979, it certainly appears very much like a deliberate act/provocation by the Taiwanese in this instance. The fact that Trump took the call is, however, a bit troubling. He has advisors who knew perfectly well that taking a call from the Taiwanese president would cause ructions diplomatically, yet they went ahead and did it anyway - Trump can say all he likes about the supposedly innocent nature of the call, but either he deliberately went along with something that he knew would cause offence to the Chinese, or his advisors did. Either way, it is not a great way for Trump to kickstart his relationship with China.