Show status as a phone icon when on mobile only
Differentiate when a user is on mobile vs desktop/browser. Show the available icon as a cell phone when on mobile only. Current implementation is confusing if someone is working or not. Showing something different for on mobile only would clear confusion and expectation of sender.
Guilherme Cinini commented
Also when driving - like with GPS app open or connected to Android Auto show an icon or status message (driving) so people do not expect immediate response while you are driving and participating in a meeting in Teams Mobile