• Windows Millennium Edition (Windows Me) is NOT supported in this release
• NT Users! It is strongly recommended that you unplug the ISDN adapter prior to rebooting your computer.
• If you are getting a CPU utilization error, update the sx2api.sys file located in the Drivers section of this web site
• The 3CISDN1 is to be used with the 3Com FEM656C product
• Works on European ISDN switches only
• Simultaneous ISDN Cable and Modem Function Not Supported
• Extended Suspend/Resume Not Recommended
• Use only the 3CISDN1 cable supplied with your kit to connect to an ISDN network. Any other cable can damage your 3Com ISDN-compatible LAN + Modem PC Card

For more information see the link below:

http://www.3com.com/mobile/pccards/upgradekit.html