Distributed control and storage for a large capacity messaging system

Abstract

The present invention provides a distributed architecture that includes multiple voice processing unit each designated as a home unit for a subscriber's messages. An incoming call is preferentially switched to the home VPU by a digital switching system under the control of a master control unit. If a master control unit determines that all lines to the home unit are busy or the home unit is otherwise unavailable, the master unit causes the digital system to switch the call to another or remote voice processing unit. The remote unit then handles the call by either locally storing a message or retrieving a message from the home unit storage over an internal message bus. If a message is stored remotely and the home unit is processing the subscriber request, the home unit can access the remote message over the internal control bus or the master control unit can switch the call routing through the switching system to the remote unit for processing of the remote message and return the switching system routing to the home unit when finished with the remote message. Each voice processing unit stores both remote and home message locally on local disc storage units. The master control unit stores subscriber related information such as the home voice processing unit for each subscriber and the location of each message for that subscriber. Comunication between the master control unit and the voice processing units is over an internal network.