The paper describes the BUNI (broadband user-network interface) Demonstrator Project (R1081) of the RACE programme which is concerned with the experimental implementation of the emerging standards for the broadband user network interface. The BUNI demonstrator network, comprising two broadband customer premises networks and two broadband switches, is explained in some detail to give the reader an insight into the complexity of the complete demonstrator. The signalling concepts are described to illustrate the innovative nature of the project and to give an indication of the facilities which broadband ISDN will offer. An overview of the services which will be available at the BUNI demonstrator site is given.