default or selected kernelversion does not have config value CONFIG_HISAX_ENTERNOW_PCI.
Result is shown for kernelversion 6.9.9

Formula-n enter:now PCI card

configname: CONFIG_HISAX_ENTERNOW_PCI

Linux Kernel Configuration
└─>Device Drivers
└─>ISDN support
└─>Old ISDN4Linux (deprecated)
└─>Passive cards
└─>Formula-n enter:now PCI card
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
This enables HiSax support for the Formula-n enter:now PCI
ISDN card.