Abstract: A fault-tolerant call-processing adjunct processor comprises a redundant, duplicated, service unit provisioning and maintenance processor), a duplicated LAN connected to both service units, and plurality of served units (voice-processing processors) each connected to both LANs. Each service unit and each served unit has a duplicate copy of mission-critical information (customer records and commands). Both service units are continuously exercised by operating in an active-active configuration. The service units alternate the use of the LANs, thereby continuously exercising both LANs and providing independent duplicate sources of the mission-critical information to the served units. All sending units rely on having their mission-critical communications timely acknowledged by all receiving units. Served units retry with the other service unit those communications that failed with a preferred service unit. All units store failed communications for subsequent retry.

Abstract: Calls made to an 800 service subscriber are routed to the subscriber's primary location via a telephone network switch operating in conjunction with a specially configured adjunct processor. The adjunct processor is arranged to monitor the call even after it is answered by an attendant or other subscriber personnel at the primary location. If the call is to be redirected from the primary location to an alternate location, the adjunct is signaled, typically by a DTMF sequence. The adjunct responds by putting the calling party on hold and by initiating a call to the alternate location on an outgoing trunk of the network switch, in such a way that it emulates or imitates both the routing (call treatment) and billing the characteristics of a call made from the original customer location. Redirection can then be completed in one of three ways: blind transfer, consultation, or conference.