Have a OS 7200 and the SLI card is not making a audible ring, ie. you call an SLI extension and the handset doesn't ring, however you can pick it up and the call will connect.

SLIs can ring out OK, and work normally just no ring generated on them when they are dialled internally or externally.

I had this issue years ago with a DCS and it was a bad RGEN unit in the KSU, not sure that the OfficeServ 7xxx had anything like this? The DCS500 still has an RGEN card.