Mao Zedong once said: “All genuine knowledge originates in direct experience.” This paper describes the experiences gained through a range of development projects, all concerned with the design, development, demonstration and maintenance of real broadband signalling systems. The authors have participated in the development of a variety of systems offering broadband capabilities, all of which support some form of broadband signalling between the service user and the service provider. The process of designing and building such systems can provide invaluable insights into issues such as development methods, signalling performance, programming interface definitions, etc, none of which are apparent from purely paper-based studies or through the standards specification process.
This ‘coal-face’ experience covers both collaborative as well as internal BT projects, with each system being subject to a wide variety of service requirements. In addition, the period of work covered by the developments described in the paper encompasses broadband signalling systems that on the one hand predate the published ITU-T standards on broadband ISDN systems and on the other include a comprehensive testbed supporting an interworking set of broadband signalling interfaces based on the appropriate signalling standards defined by both the ATM Forum as well as the ITU-T.