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EXTENSION IDENTIFICATION FOR A RADIO CONNECTED TO A PABX TELEPHONE NETWORK

IP.com Disclosure Number: IPCOM000007026D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2002-Feb-19
Document File: 3 page(s) / 159K

Publishing Venue

Motorola

Related People

Gary Aitkenhead: AUTHOR [+2]

Abstract

Many businesses now make use of public trunked radio systems for their mobile communication needs. They purchase a number of radios and pay a monthly subscription to a system operator. In this way, many user groups share the same infrastructure reducing the costs for small businesses who cannot afford to buy their own private system.

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MOTOROLA INC. Technical Developments Volume 20 October 1993

EXTENSION IDENTIFICATION FOR A RADIO CONNECTED TO A PABX TELEPHONE NETWORK

by Gary Aitkenhead and David Tucker

message (e.g. as available in the MPT1327 signal- ling protocol defined by the UK DTI and now a de facto trunking standard throughout Europe) to send the extension number to the fixed radio.

INTRODUCTION:

   Many businesses now make use of public trunked radio systems for their mobile communication needs. They purchase a number of radios and pay a monthly subscription to a system operator. In this way, many user groups share the same infrastructure reducing the costs for small businesses who cannot afford to buy their own private system.

  A common scenario is for one of the radios to be fixed at the company office allowing a dispatcher to contact a fleet of mobile radios. It is otten desira- ble to connect the fixed radio to the PABX network in the office. This allows anyone with a PABX exten- sion telephone to remotely control the radio and con- tact any of the mobile users in the fleet (see Figure
1). This allows a single radio to be operated by mul- tiple dispatchers.

  A problem arises, though, with incoming calls. Consider the case when a mobile user wishes to contact a dispatcher on a telephone extension via the radio system. The trunked radio system typi- cally has a signalling scheme which allows a radio to be called using its specific address code. When a user wishes to make a call to a particular extension via the fixed radio, there is generally no accommo- dation in the signalling to identify the particular PABX extension which the user wishes to contact. One method used in the past is to establish contact with the fixed radio and then send the extension over the traffic channel using DTMF tones. This requires the user to key in the number while on-air thus wasting traffic channel air-time which is usu- ally only allocated by the system for a limited time
(e.g. 1 minute).

  The solutions described below offer two schemes to provide automatic call set-up to an extension via the fixed radio. The first uses a fixed radio with mul- tiple identities, each one corresponding to a particu- lar extension, while the second utilizes a short data

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DETAILS OF THE SOLUTIONS:

  In a trunked radio system, each radio has an identification number (ident) which is used in sig- nalling to identify that particular radio. A radio will respond to an incoming call when it receives a sig- nailing packet containing its ident. This creates a problem in the case of a fixed radio connected to a number of telephone extensions via a PABX net- work. The radio does not know which of the exten- sions to ring in response to the incoming call.

SOLUTION 1

  The fixed radio can be programmed with a num- ber of different idents. Each ident corresponds to a particular telephone extension and the radio would respond to signalling packets containing any of the idents in its set. The c...