ISDN Hardware question

Hi all, A local ISP is offering a one year ISDN subscription bundled with either an internal PCI ISDN card or external USB ISDN modem. Neither of the two packages specify what sort of hardware is in the box (and they won't open it so I can see what's inside. So do we also get "software" ISDN modems like the winmodems, or are they at least all hardware? If I buy one of these, are the chances good that it will work without hassles? Thanks Hans