You have a Microsoft Teams Phone deployment that contains common area phones located in a public lobby.
You need to enable Advanced calling features on all the common area phones.
What should you configure from the Microsoft Teams admin center?
Set up common area phones for Microsoft Teams
Set policies for common area phones
Use policies to control which features are available to users on common area phones.
Set up Advanced calling on common area phones (optional)
By default, the basic calling experience will be on the common area phone's home screen, but you can turn on an advanced calling experience.
To use these advanced calling features on supported Teams phone device models, you can turn on the Advanced calling toggle in the Teams admin center or on your Teams phone device that is signed into your Teams Shared Devices account.
Turning on advanced calling capabilities requires you to purchase hardware models that can support all required capabilities.
1. Turn on Advanced calling in Teams admin center
2. Sign into the Teams admin center with a Microsoft 365 admin account.
3. From the left-side menu, navigate to Teams devices > Phones > and select the Configuration profiles tab.
4. From the list, select the configuration profile assigned to your common area phone.
5. Under the Calling settings section, find the Advanced calling toggle.
6. Turn on the toggle.
7. At the bottom of the page, select the Save button.
Incorrect:
Not C: Calling policies
Use calling policies to enable private calls, using call forwarding, or simultaneous ring on common area phones.
Note: A common area phone is typically placed in an area like a lobby or another area that is available to many people to make a call: a reception area, lobby, or conference phone. Common area phones are signed in with accounts tied to a Microsoft Teams Shared Devices license.
https://learn.microsoft.com/en-us/microsoftteams/set-up-common-area-phones