Microsoft Teams Connect is included with Office 365/Microsoft 365 Business, Enterprise, and Education subscriptions. With Teams Connect, you can create a shared channel and invite external organizations to join - AAD identity is required.
Note, if you are an Azure AD premium services user and have subscribed to the Azure AD External Identities service, external shared channels users, who are active users, will be included in your total Monthly Active Users calculation. More information can be found here: MAU billing model for Azure AD External Identities | Microsoft Docs -
https://docs.microsoft.com/en-us/azure/active-directory/external-identities/external-identities-pric...
