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Expanded Numbering Plan

IP.com Disclosure Number: IPCOM000082468D
Original Publication Date: 1974-Dec-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 43K

Publishing Venue

IBM

Related People

Boisseau, M: AUTHOR [+3]

Abstract

Described is a numbering plan for a multi-Private Branch Exchange network wherein a plurality of exchanges are linked by tie lines, in order to handle communications between subscribers of the network on a private basis using the tie line facilities. In such a network different types of calls exist. 1. Internal calls between extensions of the same exchanges; 2. In-network calls between extensions belonging to different exchanges of the network, through a transit exchange or not.

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Expanded Numbering Plan

Described is a numbering plan for a multi-Private Branch Exchange network wherein a plurality of exchanges are linked by tie lines, in order to handle communications between subscribers of the network on a private basis using the tie line facilities. In such a network different types of calls exist. 1. Internal calls between extensions of the same exchanges; 2. In-network calls between extensions belonging to different exchanges of the network, through a transit exchange or not.

Consequently, there is a need to have a directory which can be used by all subscribers in the network. This directory gives the number of all extensions of the network in such a way, that the user does not have to care about which exchange serves the extension he wishes to communicate with.

Each directory number comprises a two or three-digit prefix PX identifying the exchange serving the corresponding extension, and a THTU number (thousandth, hundredth, tenth and unity) identifying the extension. Reserved digits which are different from the thousandth digit T of extensions, are used for specific functions as operator access, trunk access, etc...

A facility exists to reduce the number of digits for extensions whose T digit is the same as the X digit of PX; in this case the directory number of an extension is P(X/T)HTU.

For an internal call, dialing of the prefix of the exchange is not compulsory, and a calling party may dial either the THTU number only or the complete number PXTHTU to call a subscriber served by the same exchange. The procedure of the figure allows both types of dialing to be handled.

For such a call, the system has to recognize which type of dialing has been used and for this reason, in each exchange, the P digit is chosen different from the...