Conference organisers do not ask people to go to conferences that are impossible to get to; neither do the refuse to help with genuine requests. Many organisers have entire departments devoted to making sure speakers turn up on time. Why not just talk to a travel agent in Iran and get them to organise it. That's what normally happens if you go overseas. Or WALK INTO the chinese consulate and ask for their help rather than waiting for an appointment. All of these options sound so much simpler. I'm on the "it's a scam" side of this argument.