As you know, you can integrate Teams with your voice systems (either on-premises using PSTN or using Microsoft Voice or a third party solution).
By default, when a Teams user, enabled for voice, make a call, his phone number is being displayed.
Teams administrators can define Caller ID policies to manage how user’s phone numbers are being displayed, either the ‘real’ user’s number, a ‘generic’ service number or anonymous caller.
In addition, they can define how incoming Caller ID’s are being managed, aka blocking or not the incoming phone number.
To manage Caller ID policies, connect to your Teams administration portal (https://admin.teams.microsoft.com) and create a new Caller ID policy (or edit the default one)
The Caller ID policy blade is accessible below the Voice\Caller ID policies