Directory Contacts not showing all contacts

When on my Android phone using the Teams app...if I try to transfer a call to another person...I hit the Transfer button and then I get a search screen...If I begin to type in the user name of another person in my company...some employees show up and others do not.

Where is this information pulled from and where do I go to make sure all my employees show up in the "Directory Contacts" section when searched for?