Pulsecom OCU-DPL5 industrial commuication switch

Pulsecom model OCU-DPL5 industrial communication module. This is marked "OCU-DPL5", "B105508-1" and "D4DALX05AA".

This is from the estate of an industrial telecommunications engineer and ham radio enthusiast. We don't know much about it. We have not tested it and the box is worn and dirty from storage.