The American Fibertek Series 89D fiber optic link is designed to interface with the Dukane STARCall and compatible 25V intercom systems. The Series 89D transmits and receives the intercom signals using either a multimode or single-mode fiber . Diagnostic indicators provide a quick visual indication of system status. Equipment may be ordered as stand alone modules or rack cards that are mounted in SR-20/2 or SR-20H/2 (for redundant power supplies) American Fibertek Card Cages.