Busy on Busy这个功能首先出现在Ignite 2016上介绍Skype for Business的新功能时出现的，意思是当拨打对方的Teams时，若对方忙线，会听到Busy Signal.
我们来简单回顾一下skype的部署过种即可
那么现在Teams上面的Busy on busy的功能也是一样，若对方忙线，会听到Busy Signal 或转到留言，原文如下：
Busy on Busy is a feature that allows callers to know if a user is already on another call or meeting when contacting them. When a call comes in to a user who is already engaged in a call or meeting, this setting alerts the calling party that the user is busy by playing a busy signal or an appropriate message.
Busy on Busy这个开关会在Teams Calling Policy中设置，到时我会把截图更在这篇Blog上面，敬请期待。
根据消息，这个功能将会在四月底开始Roll Out, 直接五月底完成全球的Roll Out
https://www.microsoft.com/en-us/microsoft-365/roadmap?rtc=1&filters=&searchterms=49990