Gordon Sondland the day after Trump's 7/25 phone call on UATV
It sounds like they are dancing around the real content of the call but Sondland name-checks Perry, Volker and Walker. She straight-up asks him why, as US ambassador to the EU, he spends so much time in Ukraine. His answer: "...he [Trump] has also given me other special assignments including Ukraine..."
Worth a view with the advantage of hindsight.