The strobe light as an extension in the queue would only work if you were using the "ring all" approach. If you are using a different polling strategy such as prioritized hunt, or least busy, it would only light up when the call is ringing at the strobe extension, and we don't really want that right? So what we really need is a listener that monitors whether there are calls waiting in the queue, and then use some facility (API) of the strobe to turn it on or off. This can be done using the Call Control API. You would need to monitor new connected calls, and check whether it is a queue extension, then turn on the light. Then monitor for delete events and then check again whether there are calls waiting in the queue and if no more calls are waiting, turn off the light. It's absolutely possible. This monitoring application would be either a Windows service or Linux daemon running on the 3CX server.