Azure Communication Services provides multichannel communication APIs for adding voice, video, chat, SMS and email to applications. Deeply connected with Teams, we now see support for Teams identities added to the Azure Communication Services capabilities.
This means developers can build applications which integrate directly with Teams users. Meaning meetings can be joined or calls made/received as a Teams user. And that all Teams user policies can be included.
An additional benefit is that Teams calling capabilities can now be brought into devices that are not supported by the standard Teams client.
You can find out more in the Microsoft documentation.