RDL ST-TC1 Stick-on Telephone System CouplerThe ST TC1 is intended to be connected to an on site telephone system switching unit KSU. It is NOT intended to be connected directly to a telephone CO line. Connections from the ST TC1 go into the telephone switching unit as if the ST TC1 was an incoming phone line. When the KSU seizes the line to the ST TC1, a relay contact closure is provided which can be used to control a variety of equipment, such as a paging system or radio system. The closure