Implement and configure Teams Phone — Microsoft 365 Certified: Collaboration Communications Systems Engineer Associate

The official AZURE documentation our Implement and configure Teams Phone practice questions are cited to. Review the primary sources, then practise.

Official references for this objective

Microsoft — Set the phone numbers included on invites in Skype for Business Online - Skype for Business Online (retired) | Microsoft Learn

Set-CsOnlineDialinConferencingUser -Identity amos.marble@Contoso.com -TollFreeServiceNumber +180045551234
Microsoft — Office 365 Enterprise, E1, E3, and E4 plan - Skype for Business Online (retired) | Microsoft Learn

Calling Plan : you can only buy this after you buy the Phone System add-on.
Microsoft — Lync Server 2013: Configure dial plans for dial-in conferencing - Lync Server | Microsoft Learn

Make sure that at least one normalization rule in each dial plan converts telephone extensions into complete phone numbers in E.164 format.
Microsoft — Office 365 Enterprise E5 (without Audio Conferencing) - Skype for Business Online (retired) | Microsoft Learn

you'll need to use a third-party audio conferencing provider. Find a third-party audio conferencing provider at Microsoft PinPoint