If you're on leave or don't want Teams Calls to ring on your mobile device, you can disable these from the notifications menu.
Open the menu at the top left of your screen and go into Notifications.
Then scroll down and toggle the Incoming calls and Missed calls settings.
Incoming calls controls whether your mobile device rings at all.
Missed calls controls whether you are notified if someone tried to call you (when incoming calls was off). This is an individual user preference.