Visual message waiting indication in a telephone voice message system

DETAILED DESCRIPTION In accordance with the principles of the present invention, the above and other objectives are realized in a telephone system of the above type by further including in the system a control means which is responsive to the message waiting indicator requests associated with the voice message system and which establishes so-called "suppressed ringing connections" through the central office switch to the subscriber locations associated with the requests.
Visual message waiting indicator signals can then be transmitted over the suppressed ringing connections to visual message waiting indicator interfaces at the subscriber locations.
These interfaces, in turn, can activate visual indicators to visually indicate the presence of a waiting message.
Subscriber locations are thus made aware of waiting messages without the need to go off-hook and without being disturbed by ringing.
In both of the embodiments of the invention to be described hereinbelow, the control means includes a central office service unit and associated telephone trunks which are configured to interact with the central office switch to establish the suppressed ringing connections to the subscriber locations.
In a first of the disclosed embodiments, the control means further includes a local control computer which controls the central office service unit and which monitors the links carrying the message waiting indicator requests to the central office switch.
In a second of the disclosed embodiments, the control means further includes a centralized control computer which controls the central office service unit.
In this case, the centralized computer receives message waiting indicator signals or requests associated with the voice message system via a data network such as a public packet switching network and routes these requests over such network to the central office service unit.
Also disclosed are various ways of effecting visual message waiting indication if a subscriber location is busy.