Blocking Phone Numbers
You can block phone numbers from the Teams application. In the Calls pane of Teams look at the History Pane in the center of the screen. Hover your mouse over the number you want to block, select the 3 dots menu, then select Block
To unblock a number click the three dots at the top right of the window next to your icon, then select Settings
On the left side a new Settings pane opened. Select Privacy, then on the right look for Blocked Contacts. Click the Blocked Contacts button
You will see a list of contacts that have been blocked. Click the Unblock button to remove them from your blocklist