This blog will touch on share mailboxes for resource accounts including Call Queues and Auto Attendants.
- In the Exchange online admin portal go to recipients –> groups ->create group
- Fill out all the information that you need; the below information would be needed as well. Also you will need to add the members to the group.
3. Once this is completed you can go under your Auto Attendant in the Teams GUI and configure as needed.
This should give you the shared mailbox option now for your Auto Attendant. I have not tested this in great detail. Feedback would be appreciated on this one.