You can enable Teams Phone Conference dial-in number and phone system greeting features for the Business Basic, Business Standard, and Business Premium

 

Add-ons

Audio Conference

Enables dial in option for Team Conference call.

Teams Phone Conference Dial-in Number

Phone System

Provides a DID and auto-attendant.  The auto attendant allows for a welcome phone system greeting, department and phone extension.  By default, you can make or receive outbound calls through Teams dial pad.

Teams Phone Conference Dial-in Number

 

A pretty good resource for set of the phone system’s auto attendant features are located at docs.microsoft.com.

 

Bundled Plan Option

Finally, you can receive Teams Phone Conference Dial-in Number and phone system greeting features all in one E5 license for $57mo per user.

 

Teams Phone Conference Dial-in Number and Phone System Greeting Summary

 

Additional Resources:

How to use Microsoft Teams with SharePoint & other key features – Network Antics

Conference Call Software Support and Reviews – Network Antics