Call coverage arrangement in an ISDN switching system

摘要

A call coverage arrangement where a covering terminal has, for each covered terminal, a single monitor lamp that not only indicates the overall or collective busy or idle status of the call appearances on the covered terminal but also the collective ringing status. Distinct visual signals are provided at the monitor lamp to indicate either a ringing while idle or a ringing while busy status. This allows all calls to be answered promptly and efficiently by a secretary in a manner which, from a human factors standpoint, is similar to the call coverage provided with key systems.