Agree with above, you need a T/A (modem for ISDN).
Some notes from experience using ISDN and these...
- Are you planning to use just one line at 64K or two lines at 64+64=128K. Some T/As only have 64, some have both. Check before buying.
- There are different types of T/A you can buy with respect to how the "attach" to your PC, e.g. internal PC card for a desktop machine, USB, serial lnk, PCMCIA card slot for laptops.
The internal desktop card and USB type might be best (fastest connection which helps from experience). Avoid serial unless your PC/Laptop is really old and you have no choice.
Just checked the Eircom pages and they only appear to sell one now at €97.
Checkout eBay, much cheaper there, see:
[broken link removed]