Busy on Busy這個功能首先出現在Ignite 2016上介紹Skype for Business的新功能時出現的，意思是當撥打對方的Teams時，若對方忙線，會聽到Busy Signal.
我們來簡單回顧一下skype的部署過種即可
那麼現在Teams上面的Busy on busy的功能也是一樣，若對方忙線，會聽到Busy Signal 或轉到留言，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這個開關會在Teams Calling Policy中設置，到時我會把截圖更在這篇Blog上面，敬請期待。
根據消息，這個功能將會在四月底開始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