Appendix: What is the ISDN?
MicroLink ISDN/PCC-16
Manual © 1997 ELSA GmbH
37
F
What is the ISDN?
ISDN stands for "
I
ntegrated
S
ervices
D
igital
N
etwork". The ISDN provides an integrated platform for
all forms of electronic communications; voice, text, data and image transfer can all be performed with
one digital connection. The advantage of digitalization is that the existing telephone infrastructure is
used, and to far greater effect. ISDN offers new and improved services via a single connection, higher
data transfer rates (64,000 bps) with improved quality and security, and all with the use of an
internationally standardized interface, the S
0
/S
2M
.
The History of ISDN
1979
The German Post authorities decide to develop a digital telephone network
1982
The German Post authorities declare their intention to adopt the ISDN
standard for the digital telephone network
1984
CCITT release a comprehensive set of recommendations for ISDN
1986
ISDN pilot project in Mannheim and Stuttgart (D), with more than 400 ISDN
basic connections
1988
ISDN as standard in operation
1989
Foundation of Euro-ISDN: 26 network operators from 20 countries sign the
"Memorandum of Understanding" (MoU)
Since mid-1993
ISDN connections to Australia, Austria, Belgium, Denmark, Finland, France,
Great Britain, Hong Kong, Italy, Japan, Luxembourg, the Netherlands, Norway,
Singapore, Spain, Sweden, Switzerland, and the USA.
Late 1993
Euro-ISDN (DSS1) introduced to Germany
1994
Nationwide ISDN coverage in Germany
Until 2000
The German national ISDN (1TR6) will continue to be offered by the Deutsche
Telekom.
The Services
The new and improved services include:
n
Interference-free telephony with constant volume, quicker connection and a higher speech
bandwidth (7.1 kHz)
n
Fax transmission with the group 4 standard for improved transmission quality and higher
resolution (400 dpi). The transmission time for an A4 side takes about 10 s. Unfortunately, fax
transmission with group 4 is not compatible with group 3 recievers.
n
The transmission of news via Teletex
n
Access to T-Online/Datex-J/Btx (in Germany) at up to 64,000 bps instead of analog's best of
33,6000 bps
n
Video telephony with (slow) image data transfer
n
The continued use of analog end devices via an a/b terminal adapter
