This chipset is used in low-end passive ISDN BRI cards, typically used for Asterisk etc.
As of June 2006, I had no luck getting these cards to work with the HEAD branch of mISDN and any recent (2.6.14, 2.6.15, 2.6.16) kernels. The cards would be recognised via misdnportinfo, and misdn-capi would bind correctly and show up via capiinfo. Incoming calls to Asterisk would be connected, however no sound would play and they would disconnect after a short period. Outgoing calls would not connect.
In the end I got this working using Debian's 2.6.8 kernel and an old version of the drivers, as per this mailing list post
I'm not at all happy with the fragile state of this setup, so I will keep an eye out on the state of this problem to see if it gets solved in the future