You can add an external guest to a team, allowing you to coordinate, communicate, and plan with vendors, contractors, and other outside collaborators.

If your guest doesn't already have a Microsoft account they can use to sign in, a one-time code will be sent to their email on each login, as is the case with guest access to other Office 365 services.

Note: Guests cannot be added to shared channels.

Helpful Resources from Microsoft

• Add guests to a team in Microsoft Teams
• Guest experience in Microsoft Teams