Operation Manual

AVM System Architecture
Controller C4 – 6 AVM System Architecture 27
6 AVM System Architecture
This chapter provides information about the ISDN applica-
tions interface CAPI 2.0, about the IDM architecture, the AVM
system drivers included with the ISDN-Controller C4, and
about special CAPI features of the AVM ISDN-Controller C4.
6.1 The Applications Interface CAPI 2.0
Upon successful installation of the AVM ISDN-Controller C4,
the ISDN interface CAPI 2.0 is available in the system. This
allows applications to use all the features of ISDN.
What is CAPI?
Common ISDN API (CAPI) is a standardized software inter-
face that provides applications with access to ISDN adapters
on basic-rate and primary-rate lines. Applications that build
on this standard interface use uniform mechanisms for com-
munication over ISDN connections, and thus do not need to
adapt to the peculiarities of particular manufacturers’ hard-
ware. This means that these applications are also unaffected
by future extensions or hardware modifications: CAPI makes
such changes transparent to the application. ISDN hardware
manufacturers benefit from this standard too, since it makes
a wide range of applications compatible with their products.
CAPI contains an abstract definition of ISDN services which
is not dependent on the specifics of the underlying telecom-
munications network or the adapter card used to connect the
computer to ISDN. The specification provides an interface
that is easy for applications to use, and thus offers uniform
access to the various ISDN services like data, voice and fax
transmission, video conferencing and telephony.
Advantages of CAPI
CAPI has evolved into an internationally recognized stan-
dard. The key factor in this development has been the nu-
merous advantages offered by this uniform interface: inde-