Industrial telecommunications Ericsson repeater system module

Industrial telecommunication network module from the estate of a communications engineer. We don't know much about this, but we were told that is is made by Ericsson and is used with industrial repeaters. This module is marked "System Model", "Transmit", "Rem Ptt", "Tx Disable", "CG Monitor" on the front panel. It is also marked "19D902590G6"and "R8A System Module" on the back. It is stamped "SLR 140" on the metal cover.