Ignoring a call he had smoke in the cockpit would not be ignored in the US. I had it and the handling was fine with no maydays. Trucks were there and we didn't have to say roll the trucks or mayday. We are declaring an emergency did everything. 23,000 hrs in US flying and zero ATC problems. Aruba is another issue on ATC problems. Also Caracus, cenamar, Dominican republic and a few other third world countries. Thank God for TCAS in some of these places. We went over Swan Island at FL350 one day going to central america in the clouds and reported Swan Island on the hour at FL350. 30 seconds later World Airways reports Swan Island at 01 at FL350. I asked, World, what direction are you going? He said SE, I was going S so quit worrying about him. It can get scarey down there. The TCAS I had was in a 727 and only looked forward so I do not know how far he crossed at our altitude behind us.