Abstract: An incoming call received in a private branch exchange (PBX) or other communication system switch at an external port of the switch is processed by the switch so as to appear to a destination terminal as if it were originated by an internal extension associated with the switch. The incoming call may be from a mobile telephone or other originator terminal that is utilizable external to a premises serviced by the switch and does not have an extension associated with any internal endpoint serviced by the switch. The switch attempts to map an identifier associated with the incoming call to a corresponding entry in a stored list of external endpoints registered with the switch. If the identifier has a corresponding entry on the list, the switch processes the incoming call such that it appears to the destination terminal as being originated by an assigned internal extension. For example, an internal alerting indicator and associated station display may be provided at the destination terminal.

Abstract: Ordinary alarm conditions are escalated into a critical alarm condition by first accumulating the ordinary alarm conditions. Upon each ordinary alarm condition, a number of previously accumulated alarm conditions are deleted in accordance with the elapsed time since the last alarm condition. When the number of accumulated alarm conditions (less those deleted) exceeds a threshold, a critical alarm condition is then generated.

Abstract: When a subscriber to message retrieval service retrieves a message, rather than reporting a time of day associated with the message that may not have any meaning to the subscriber if the subscriber, the message originator and the message depository are in diverse worldwide locations, the disclosed message retrieval system reports a delta time indicating to the retrieving subscriber the time elapsed since the message originator delivered the message.