As previously announced at Ignite, you can invite any Teams user to chat by entering the full email address or phone number you want to reach and start a 1:1 or group chat with anyone with a Microsoft personal account, no tenant switching required. You can restrict external access by allowing or blocking specific domains or by turning it off. If youre typing a name and its not showing up as a suggestion, it could be theyre not a member of the chat youre @mentioning them in or, if its a channel conversation, they may not be a member of the team to which the channel belongs. Step 2: In the left hand sidebar you will see four different icons.