Operation Manual

Appendix The Applications Interface CAPI 2.0

As early as 1989, ISDN manufacturers began develop-

ment work on a standard interface for the rapidly expand-

ing ISDN market. The first version of CAPI concentrated

on the German national ISDN protocol 1TR6, as an

international standard for ISDN protocols was not yet

available. In 1990 development was complete, and a

CAPI Working Group was formed by ISDN application and

hardware manufacturers, large-scale ISDN users, user

groups and the German PTT, at that time DBP Telekom.

CAPI Version 1.1 was a milestone in the development of

the national ISDN market in Germany. Today all German

ISDN solutions and a large proportion of international

products are based on CAPI.

The international standardization of ISDN-protocol speci-

fications is now complete, and nearly all telecommunica-

tions network operators provide BRI and PRI lines on the

basis of the international standard Q.931/ETS 300 102.

With CAPI 2.0 a version based on this standard now is

available.The experience gained in Germany and other

countries over the past years in the development of an

ISDN applications programming interface, along with the

enormous base of installed CAPI solutions, have contrib-

uted greatly to the development of this new applications

interface for international ISDN systems.

Over ten years of experience in the growing ISDN market

have gone into CAPI 2.0. This version has all the

advantages of an open interface and covers most ISDN

features (including data communications, telephony,

Group 3 fax and video conferencing). Since CAPI handles

ISDN subscriber interface control functions, these no

longer have to be programmed. This simplifies the

development of ISDN applications. Furthermore, appli-

cations no longer have to be tailored to national or

manufacturer-specific systems, so that a greater variety

of applications is available.

By using CAPI Version 2.0, the international market

benefits from comprehensive technological know-how

with great profit potential.

CAPI 1.1

CAPI 2.0