At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Mahmood Ahmad

Wayne L Schreiner

Albert Joseph Sawyer

Gerald H Thomas

A distributed control switching system where the system control units cooperatively perform the terminating port determination function. The control unit associated with the terminating port stores sequence call data defining whether calls are to be completed to that terminating port or are to be forwarded to another directory number. Upon determining that a given call is a sequence call, the control unit associated with the original terminating port determines the terminating port defined by the second directory number and effects a reduction of the sequence call to a simple call between the originating port and the second terminating port. This is done either by transmitting a control message defining the originating and terminating ports to the control unit associated with the second terminating port or by returning the setup sequence to the control unit associated with the originating port which then frees any switching system resources previously allocated to the call and transmits the control message. In either case, the control unit associated with the second terminating port completes the call without knowing whether the call is a sequence call or a simple call completed to the original terminating port.

Processing sequence calls in a distributed control switching system

A distributed control switching system where the system control units cooperatively perform the terminating port determination function. The partial results obtained when a first control unit is unable to fully determine the terminating port are advantageously used by the second and subsequent control units such that time-consuming database access tasks are not unnecessarily repeated.

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Winfield, IL, United States of America

Mahmood Ahmad