Importance

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Abstract

At least three private branch exchange program-controlled telephone equipments (PBX's) in different countries form a system in which the PBX's are interconnectible by direct tie lines, tandem lines or direct distance dialing lines. Each PBX is equipped with the feature of Automatic Route Selection ('ARS') which, when a subscriber at an extension of a one such PBX in one country dials the full string of digits used for an international call to a remote station in another country, selects, out of the tie lines, tandem lines and direct distance dialing lines outgoing from such PBX, an idle one of such lines providing for such call a transmission route yielding the least cost for completing that call. Each such PBX includes the improvement feature of modification of the code signals produced by the dialing of such string of digits to cause outpulsing from such PBX of only those of such signals which are necessary for completion of the call over the transmission route selected therefor by ARS. That feature is realized by holding such code signals, deriving, from stored data relevant to the several transmission routes for calls from such PBX to the remote station, information on the dialed signals which are necessary for completion of the particular call over the particular route selected for it by ARS, and, on the basis of that such information, modifying the held dialed signals to leave only those determined as being necessary for completion of the call over the route selected therefor prior to transmission of such dialed signals over such route.

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First Claim