In Teams, you can call in to a meeting by going to the Calendar 
If you’re not a member of Teams, you can still join a Teams meeting from an invitation you received in Outlook or another email application. Use the phone number provided to dial in to the meeting.
Instead of joining online, you can call in to a meeting with your phone. To get the phone number, tap the meeting or meeting notice and select See details. You'll see a phone number that you can use to dial in.
If you’re not a member of Teams, you can still join a Teams meeting from an invitation you received in Outlook or another email application. Use the phone number provided to dial in to the meeting.
