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