You can add each person in your office/team as a contact onto the Yealink phone and record their internal extension number so that you can then transfer calls over to people when necessary. 

To add a person as a contact on the phone press the 'Directory' soft key

Then press 'Enter' 

Then press 'Add' which then gives you the ability to add in a name i.e. Stan and for the Office Number: add the contact's extension number

Press 'Save' when finished.