Software development and testing methodology used for subscriber digital concentrator ACK-2000

The paper presents a software development and testing methodology, which was used for the new version of the subscriber digital concentrator ACK-2000. This concentrator was developed for the Russian telecommunication network. During the development process special attention was paid to precise software specification, professional implementation, and testing/redesign, in order to reach the given criterion of 0.1% of unsuccessful calls. The tests, which were conducted, include functional tests and real-time load tests, with the real exchange and the call generator connected to the subscriber lines. The results of these tests and software reliability analysis are reported