Hello Mia I,
From public official document, UDP port 3481 and TCP port 443 both are needed for service connections, media flows of Teams meeting and conferencing (including live events). In general, UDP ports are often used for media transmit: Prepare your organization's network for Microsoft Teams -- Network requirements
These ports are very important especially for Business Voice: Make sure the computers and devices on your network can reach Microsoft 365
Public information might be limited, however, if you encountered any call quality issue, it’s also recommended to use Teams admin center to analyze it. For example, in Teams admin center -> Users -> select one user and select Call History -> then you can see the full meetings, calls and live events list this user participated in, select one session from there -> it will show sub-session for each participant, click one that belongs to this user account -> We can then check Overview, Advanced and Debug information:
Furthermore, if your organization has more complicated and strict network requirement, you can refer to this article to check more details : Evaluate my environment
Best Regards,
Anna
