Abstract :
A private telecommunication network (PTN) includes those parts of the corporate network that provide voice, narrow- and medium-band communication services. Such networks traditionally comprised of dedicated switching equipment (PBX) and dedicated transmission (leased lines). As an introduction, PTN services, interfaces and the supporting signalling protocols that are being standardised in Europe (ETSI and ECMA) and internationally by ITU-T (formerly CCITT) and ISO/IEC are summarised. These standardisation activities follow and are in the main compatible with the standardisation of public ISDN. The main topic of the paper is hybrid PTN which in addition to PBXs and dedicated transmission also contains network components that are implemented in the public network such as Centrex nodes and the use of VPN services for transmission. The specific signalling mechanisms used in PTNs are examined firstly, and secondly the various ways by which the public network infrastructure can both support and interwork with intra-PTN signalling are expanded
