How Does an ISDN-Controller Work?
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FRITZ!Card – 5 How Does FRITZ!Card Work
5.2 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
0
bus and thus to the local exchange of the telephone net-
work.
Any telecommunication service, for instance Internet, Fax G3
or telephony, is implemented using “protocols”. Protocols
stpulate the procedures used for data transmission between
the subscribers. They ensure smooth communication and
adjust such parameters as transfer speed and data compres-
sion 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 driv-
er 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 sta-
tion. 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 driv-
er software for the ISDN-Controller FRITZ!Card thus is also
known as the CAPI driver.
While every FRITZ!Card has a special CAPI driver for each op-
erating system supported, the applications work identically
and 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 ISDN NDIS WAN CAPI Driver for pro-
grams that require a modem or a network adapter.
Summary of Contents for FRITZ!Card PCMCIA
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