This Design Guide provides guidance on the technical requirements for any Private Network (PN) within Australia comprising various combinations of switching and transmission equipment facilitating the establishment of calls within and between Private Networks and, in situations where these networks interwork with the Public Telecommunications Networks, the requirements for such interconnection. Connection to the telephone network is considered at the customer level only. This Design Guide addresses mainly voice aspects. Information on data aspects will be progressively included in subsequent issues.Throughout this Design Guide, the International System (SI) of units and symbols is used in accordance with Australian Standard AS 1000.This Design Guide is an advisory document and compliance with it is voluntary. Where interconnection with Public Telecommunications Networks is required, conformance with AUSTEL's Technical Standards is mandatory, and these should be consulted.Documents referenced to in this Design Guide are those issues current at the determination of this Design Guide, or where appropriate at subsequent revisions of this Design Guide.Notes for guidance on interpretation are shown in smaller size typeface.In the event of any discrepancy between AUSTEL's Technical Standards and the references called up in this document, AUSTEL's Technical Standards shall take precedence.This Design Guide is intended to be a 'living document', subject to revision as warranted by changes in regulation, markets and technology. Representations concerning the need for change should be addressed to: The Manager Industry Standards Branch AUSTELPO Box 7443 St Kilda RoadMELBOURNE VIC 3004