Copper, but not ISDN. Fractional E1 leased line. There were expensive and limited ISDN connections available in Norway at the time ('95), but not cost effective for an ISP.

If I remember right we could get 64kb/s or 128kb/s if you bundled them, that was in Germany. But also, we didn't have that, we only had a 56kb/s modem and I remember really wanting ISDN when I was a kid :)