Telephony over Teams offers you the ability to make, receive, and transfer calls through your Teams client. You can also handle voicemails, view call history, set up call queues, and delegate calls to colleagues.
The following video, created by the IT Learning Centre, gives you a flavour of what Telephony over Teams looks like and how it works. For more detail and guidance, please see the section below.
https://web.microsoftstream.com/embed/video/d3d26d79-29fe-40b1-8479-eb244a51de0c?autoplay=false&showinfo=true
This is not an exhaustive list of functionality, but it should help you get started: