asterisk users - Nov 2005 - AT&T Merlin Communications System 6102 Cartridge Music on Hold and Paging

I am trying to replace the overhead paging function of an old phone
system. There is a device with an RJ11 connection connected to two
screws on the phone system. The two screws are on a cartridge labeled as
the subject of this message. 

I thought the other device was probably a station andthat I could plug
it into an ATA and send it a call to come out on the speakers. 

I was wrong...anyone know anything about this and how that box might be
wired? 

More importantly, does anyone know how to make it work with an asterisk
system? 

-Jonathan