Normally, Teams meetings are held with internal staff. However, sometimes you may need to have a meeting with someone outside the company.
First, go to your Calendar in Teams. You will see two options: Meet Now, and New Meeting.
New Meeting will allow you to make a calendar invite, which you can send to any email address.
However, if you need to create a meeting for external users to join immediately, click Meet Now. Name the meeting whatever you want, and then click Start Meeting.
When the meeting starts, you'll see the following options. Click Add Participants.
At this point, what you need to do is copy the meeting link. You can then send this via any method - email, SMS, instant message, etc. - and whoever you share this link with will be able to access the meeting.
If you participants are not sure what to do, instruct them to click the link and then Continue on This Browser.
When they join the meeting, you will need to admit them. A box will show up on your screen.
If you have additional participants, they may not show up straight away. To admit more guests, click the Participants icon - each guest who is waiting will be marked by a number in a red circle on the icon.
They will show up on the right of the window. You can also get the link from here if you didn't get it earlier, by clicking Share Invite.