1975 ONWARDS (continued)

Returning now to the PSTN, integration of digital switching and transmission results in an Integrated Digital Network (IDN) which switches speech traffic using 64 kbit/s transmission as the basic speech circuit instead of the standard 4kHz channel in the analogue network. The 64 kbit/s path naturally enables other uses than speech and thus is a basis for the integration of data with speech. Accordingly, Telecom has planned for the general availability of a switched 64 kbit/s transparent service between terminal exchanges to meet telephone demand and to develop various network capabilities and customer services on this. A feature of the plan is the development of the IDN as an overlay network interworking with the analogue one. The introduction of Common Channel Signalling (CCS) is an integral part of the IDN plan as it offers the prospect of improved facilities without increasing cost, reduced call set up times, improved circuit utilisation and facilitates introduction of enhanced network services.

In 1983 and 1984 Telecom and OTC collaborated with KDD Japan in the first intercontinental field trial of the CCITT No. 7 signalling system, the later generation common channel signalling system designed to be the central nervous system of the Integrated Services Digital Network. In this field trial, signalling terminals independently designed and built at Telecom's Research Laboratories in Melbourne and at KDD's Research Laboratories in Tokyo, were found to interwork successfully via satellite radio links and submarine cable links, thus providing confidence in the CCITT's draft international specifications for No. 7 signalling, written in the CCITT's graphical Specification and Description Language (SDL). The field trail also provided useful experimental data on the comparative performance of three alternative error protection schemes permitted in the 1980 CCITT specifications of No. 7 signalling.[61] Common channel signalling was introduced into the national network in 1986, following these earlier trials.

Another step in the process of providing a comprehensive communications service came in September 1981 when a fully automatic mobile telephone service with a capacity for some 4,000 customers, using 120 radio channels in the 500 mHz band, began operation in Melbourne with similar services following in Sydney, Brisbane, Perth, Adelaide and the Gold Coast. Introduction of the service followed a survey of overseas technology, detailed examination of the Australian market, estimate of likely traffic needs, which together showed that the system required was larger than then available in the world. Following analysis of the results of a tender call in 1977, a contract was entered into with NEC to develop a system to meet Australia's particular requirements.[62] Mobile telephone technology continued to develop rapidly and to meet the rising demand for the service, specifications were developed for a high capacity cellular module telephone service and tenders let for a service to commence late in 1986 or early 1987.

Viatel, a public videotext service provided by Telecom, based on the UK's Prestel service, began operation in 1985. The system enables the user to retrieve information from databases and to carry out transactions on external databases, including ordering products and services, banking and sending messages.[63] The basic computer equipment was supplied by G.E.C. but software packages to enable access to Viatel were Australian designs, as was an improved gateway protocol concept.

Australian Academy of Technological Sciences and Engineering