Overview
You have two options when it comes to using audio with Microsoft Teams: integrated audio or Microsoft 365 Audio Conferencing.
Detail
Integrated Audio: Voice over Internet Protocol (VoIP)
Integrated audio uses VoIP and your computer's microphone and speakers for the audio portion of a meeting. If you have a Microsoft Teams handset or headset—or a webcam with a built-in microphone and speakers—you will be able to use this feature.
There is no cost for connecting to the audio portion of a meeting or conversation using VoIP.
Microsoft 365 Audio Conferencing
If you are unable to use Integrated Audio, Microsoft 365 Audio Conferencing allows you and other meeting participants to join the audio portion of the meeting using a phone. If you have Microsoft 365 audio conferencing, the dial-in conferencing numbers appear below the "Or call in (audio only)" heading in your meeting invitation.