Operation Manual

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Appendix B: The Applications Interface CAPI 2.0
English
Appendix B:
The Applications Interface CAPI 2.0
B.1 Introduction
Common ISDN API (CAPI) is a standardized interface
that provides applications with simple access to basic
rate and primary rate ISDN adapters. Applications that
build on this standard interface use uniform mechanisms
for communication over ISDN connections, and do not
need to adapt to the peculiarities of different
manufacturers’ hardware. This means that such
applications are independent of future extensions or
hardware changes. CAPI makes such modifications trans-
parent to the application. ISDN hardware manufacturers
themselves benefit from the standard too, since it makes
all kinds of applications compatible with their products.
Common ISDN API contains an abstract definition of
ISDN services which is not dependent on the specifics of
underlying telecommunications networks or the adapter
cards used to connect computers to ISDN. The
specification provides an interface that is easy for
applications to use, and thus offers uniform access to the
various ISDN services, such as data, voice and fax
transmission, video conferencing and telephony.
Common ISDN API has evolved into an internationally
recognized standard. The key factor in this development
has been the numerous advantages offered by this
uniform interface: independence from specific
manufacturers and resulting high investment security, a
wide variety of compatible applications for all kinds of
operating systems and ISDN protocols, etc. ISDN (the
Integrated Services Digital Network) is becoming
attractive for more and more companies, since it affords
fast and reliable transfer of information in many different
forms.
As early as 1989, ISDN manufacturers began development
work on a standard interface for the rapidly expanding
CAPI 1.1