I did my test on WiFi which results in almost instant calls for me. Set your computer to catch the facetime call and answer it automatically (check this: https://github.com/PaperCutSoftware/teleportme/blob/master/t...). Capture your screen continuously and if you might get the first frames of the call. It's all about what people do when their phone starts calling by itself. Most people freeze which results in a successful attack.