In Microsoft Teams, audio conferencing PINs are used by meeting organizers to identify that they are the meeting organizer and allow them to start a meeting over the phone. If they use the Microsoft Teams app to start the meeting, a PIN isn't required.
If you would like to reset your PIN, you can do so by logging in to the Teams User Settings page and clicking the "Reset PIN" button under Audio Conferencing settings:
NOTE: the Teams audio conferencing feature is only available to UIC Faculty and Staff who have A5 Microsoft 365 licenses assigned.