We have 4 identical iMacs set up in identical ways. They all use the same Apple ID and that same email address is being used for FaceTime. When I take my iPhone (using a different FaceTime ID) and ring that email address to do a FaceTime call, only ONE of the iMacs receives the call (rings and displays that someone is calling). The others ones don't react to it at all, even though they are identical in every way I can think of. All the iMacs can make a FaceTime call to my iPhone just fine, and they show up as the Apple ID they are using. What the hell is going on and what can I do to troubleshoot this? I thought FaceTime can work on multiple devices with the same ID, and that all devices should ring simultaneously when getting called? It's so frustrating and unintuitive, why can't it be as simple as Skype?