(CAPI, Common-ISDN-API) A programming interface standard for an application program to communicate with an ISDN card. Work on CAPI began in 1989, focussing on the German ISDN protocol, and was finished in 1990 by a CAPI working group consisting of application providers, ISDN equipment manufacturers, large customers, user groups and DBP Telekom, resulting in COMMON-ISDN-API Version 1.1. Following completion of the international protocol specification, almost every telecommunication provider offers BRI and PRI with protocols based on Q.931 / ETS 3009 102. Common-ISDN-API Version 2.0 was developed to support all Q.931 protocols.