Pabx through connection of extensions to public network - uses common control initiated relay closures to directly connect extension to public network through a connection unit

摘要

Switching relay operation for connecting extensions on a PABX through to the public network in the dial inter train pause period and by using the PABX common control. The extension (NA) and public network (OEF) are connected using a relay contact connected signal transmission unit (VU). The PABX common control (ZF) responds to seizures and uses relay switching (Z,F) to connect extension (NA) to public network (OEF) using a low resistance relay contact path (r1,4d,5d etc.).