ISDN ISDN ISDN technology allowing the transmission ISDN (Integrated Services Digital ... ISDN ISDN Integrated Services Digital Network ISDN (Integrated Services Digital Network) ISDN ISDN ISDN ISDN ISDN ISDN (Integrated Services Digital Network) ISDN ISDN (Integrated Services Digital Network) ISDN ISDN (Integrated Services Digital Network) ISDN Integrated Service Digital Network (ISDN) ISDN ISDN ISDN integrated services digital network ISDN ISDN ISDN ISDN Integrated Services Digital Network ISDN lines ISDN Definition Integrated Services Digital Network ISDN Integrated Services Digital Networks ISDN ISDN ISDN