it says SONET on it. that's your hint right there. sonet is a phone co networking protocol for realtime data (voice, historically).
useless to anyone who does not have sonet rings at home (ie, none of us)
Well that makes sense because the company that was selling the equipment focussed on fiber data/audio pretty heavily. So there is no use practically for this, and is just used for an old protocol? Okay, it probably wouldn't sell on Ebay then, so I might as well rip it apart and see if there is anything interesting internally
Thanks for the explanation!