How Does An Isdn-Controller Work - AVM FRITZ!Card USB Installation Instructions Manual

How Does an ISDN-Controller Work?

4.2 How Does an ISDN-Controller Work?
An ISDN-Controller serves as the connection between ISDN
and your computer. The ISDN cable supplied connects to the
S bus and thus to the local exchange of the telephone net-
0
work.
Any telecommunication service, for instance Internet, Fax G3
or telephony, is implemented using "protocols". These
protocols define how data transfer between the subscribers
takes place. They ensure smooth communication and adjust
such parameters as transfer speed and data compression
during transmission. Both communications partners must
support the protocol to be implemented, for example T.30 for
G3 fax or HDLC transparent for the Internet. The driver
software for the ISDN-Controller FRITZ!Card must support the
right parameters for every connection and pass them on in
real-time to both local applications and the remote station.
Transfer to the communications software takes place in the
computer via the COMMON-ISDN-API interface, CAPI for
short. CAPI establishes the connection between the ISDN-
Controller and the installed applications like FRITZ!. The
driver software for the ISDN-Controller FRITZ!Card thus is also
called a CAPI driver.
While every FRITZ!Card has a special CAPI driver for each op-
erating system supported, they all provide the same CAPI 2.0
functions to application programs, which therefore can be
used universally with CAPI 2.0. The modules of the FRITZ!
communications software are also based on CAPI 2.0, as are
a number of programs by other manufacturers. AVM provides
the system drivers AVM ISDN CAPI Port Driver and NDIS WAN
CAPI Driver for programs that require a modem or a network
adapter.
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