CONFIG_ISDN_CAPI_MIDDLEWARE (not configurable)

configname: CONFIG_ISDN_CAPI_MIDDLEWARE

Linux Kernel Configuration
└─>Device Drivers
└─>ISDN support
└─>ISDN_CAPI_MIDDLEWARE
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
This option will enhance the capabilities of the /dev/capi20
interface. It will provide a means of moving a data connection,
established via the usual /dev/capi20 interface to a special tty
device. If you want to use pppd with pppdcapiplugin to dial up to
your ISP, say Y here.

depends
CONFIG_ISDN