Source : Free On-Line Dictionary of Computing

User Network Interface
     
         (UNI) An interface point between
        {ATM} end users and a private {ATM switch}, or between a
        private ATM switch and the {public carrier} ATM network.
     
        The physical and {protocol} specifications for UNIs are
        defined by the {ATM Forum}'s UNI documents, which allow for
        various types of physical interfaces.
     
        See also: {NNI}
     
        (1999-01-23)