At&t Bell Laboratories

David A Redberg

Larry W Kirsch

David L Sprague

This application discloses a system for eliminating a busy line condition and completing a call over a virtual private line when the stations at each of the lines attempt to initiate a call simultaneously. The system is implemented in three phases. In a first phase, the busy line condition is detected by either the communication switching system which sets up the virtual private line or by two signal converters, each connected to a station set at each end of the line. In a second phase, the switching system or the converters send terminating supervisory signals towards each station to terminate the attempted initial calls while the stations are still off-hook. In a third phase, a predetermined signal converter or a selected switch in the communication switching system initiates a new call by emitting an originating supervisory signal while the stations are still off-hook.

System for elminating glare in virtual private line circuits

This invention relates to a method and apparatus for providing point-to-point line service by providing a switched communication circuit only whenever either terminal of the private line service lifts its receiver. In a departure from the prior art, and in order to ensure that no other stations can get access to the private line terminals, the service is provided by assigning both terminals to a common software defined network, and by routing the call through the software defined network using a non-dialable routing number derived from the identity of a calling station. Whenever either terminal lifts its receiver, a connection is set up within the software defined network; this prevents callers from outside the software defined network from accessing either terminal. Alternatively, an ingress switch of a public switched network can directly provide a non-dialable routing number for routing a call from a station that has gone off-hook to a predetermined destination identified in such a way that it cannot be reached by dialing a call. Advantageously, fully private line service is provided without requiring dedicated facilities.

Growing community of inventors

Red Bank, NJ, United States of America

David A Redberg