All ISDN functions can be selected via the menu and configure (call forwarding, Maklen, etc)
For the permanent call forwarding, mute and unique CLIR there direct dialing keys.
Of course, there's also a (limited) phonebook, a speakerphone, on-hook dialing or a connection for a headset.
All in all a standard ISDN telephone ... simple, clear, robust
* And I wonder why I have not already bought ....