Reliability and evolvability: requirements for the design of ISDN communication software

The ISDN (integrated services digital network) is characterized by the breadth of services to be supplied and the complexity of the protocols involved. Moreover, the ISDN services evolvability is an essential requirement which must be taken into account by telecommunication systems schedule. An approach to improving the quality of telecommunication products is described that is based on a formalization of communication functions. The compilation of the specifications provides a means of validation and allows the generation of an implementation and of qualification tests. This process is illustrated by an example of its use on an Alcatel E10 system component