SGA A0642B Telephone Line Isolation Unit. By law any radio, amplifier etc connected to a telephone system (for background music or paging applications) must be isolated with a line isolation unit (LIU). Adjustable output level suits all telephone systems. Supplied with 1 x 3.5mm to RJ11 cable and 1 x 3.5mm to RJ10 cable. Other output leads sold separately to suit your application.