Nortel Networks Corporation

Pat Carstensen

Ronald Schwartz

Allan Melnyk

To provide station number portability within a cluster of switches interconnected in a communication switching network each switch within the cluster is provided with two translation tables stored in the main memory of the switch processor. When digits are dialled to connect a station with another station the office code of the dialled station is extracted and if this is an office code of any switch in the cluster the first translation table instructs that a translation be carried out in the second table. The second table contains all the station numbers which are in the cluster and relates these numbers either to a physical line or to an instruction to route to another switch. When a station is 'ported' i.e., physically disconnected from one switch and reconnected to another switch, a minor change is made to the second translation table of the two switches to retain portability.

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Durham, NC, United States of America

Pat Carstensen