Partner ACS R6.0. Site had two extensions that weren't ringing. I set both extensions to Immediate Ring via Centralized Programming (FEAT 00 LI LI RI EXT IMMED RING on all four line buttons) and made sure the volume was turned up on both extensions. Test calls confirmed that both extensions were now ringing, so all was well. Site just called me four hours later to tell me that the problem had returned, however. Did I miss something, are the phones bad, is the Processor not holding the programming somehow, or are there poltergeists at work here?