ISDN (Integrated Services Digital Network)

ISDN is a wide area networking technology used from the mid/late 1980s to about 2015. It was offered in many countries around the world as the logical incremental step after telephone-network inter-office trunks and switches were converted to digital technology based on PCM technology.

ISDN was popular to differing extents. In Germany, it was widespread even for private house-holds. In other countries like the UK or the US, it was available but typically used only by businesses.

ISDN is one focus aree of our activities since 2022.

We collect, document, maintain and restore any kind of ISDN hardware, including

• ISDN telephones

• ISDN video phones

• ISDN fax machines

• ISDN terminal adapters (for analog phones, data calls, X.21, X.31, etc.)

• ISDN computer interfaces (USB, PCI, ISA, ...)

• ISDN PBXs (private branch exchanges)

• ISDN central office switches (like EWSD)

• ISDN transmission technologies (LT + NT for BRI, PRI, etc.)

• ISDN test + measurement devices

When we say document, we usually mean

• taking exterior and interior (printed circuit board) pictures at high resolution

• dumping firmware EPROMs (at least if they are socket-mounted)

• collecting data sheets of the ICs used in those devices

• collecting (and as needed, digitize/scan) user manuals and other documentation materials

• collecting drivers, configuration software, etc.

This information is typically added to the device-specific page in our wiki.

You can find more information at our ISDN related wiki pages.