IBM International ISDN User Manual page 37

Installing the IBM International ISDN PC Card in Windows Millennium Edition
10. In the next dialog, select the appropriate D-channel pro-
tocol for your ISDN line. For newer ISDN lines in Europe,
select DSS1, the Euro-ISDN protocol. NI-1 and 5ESS are
D-channel protocols used in the USA. 1TR6 is the older
national D-channel protocol for Germany.
Although some older ISDN lines in Germany still use
the D-channel protocol 1TR6, DSS1 is generally prefera-
ble. The 1TR6 protocol is no longer very common and
may be excluded from future driver releases for this
adapter.
11. Once you have selected the appropriate D-channel pro-
tocol, click "Continue".
ISDN PC Card – 6 Installing the Device Drivers in Windows® Millennium Edition 37