To reflect on the actual situation it can be stated that the international protocol specification is finished and almost every telecommunication provider offers BRI / PRI with protocols based on Q.931 / ETS 300 102. COMMON-ISDN-API Version 2.0 was developed to support all Q.931 based protocols.

Experience in ISDN application interface design, knowledge of the market needs and a large installed base of COMMON-ISDN-API solutions (hardware controller and applications on top of different operating systems) result in the necessity of developing a new application interface, usable in international ISDNs.

COMMON-ISDN-API includes more than 10 years of ISDN business implementation experience in an exploding market. It covers all benefits of CAPI Version 1.1 plus new aspects of ISDN. It is based on Q.931 / ETS 300 102 but not limited to these. It simplifies the development of ISDN applications through many defaults which need not to be programmed. It keeps applications free of ISDN protocol knowledge and thus makes application development easy.

By using COMMON-ISDN-API the international market can exploit the available experience and realise a large growth.