Internal Program Version: mISDNuser  2.1.1

mISDN supports a complete BRI and PRI ETSI compliant DSS1 protocol
stack for the TE mode and for the NT mode. It is the successor of
the "old" isdn4linux subsystem, in particular its "HiSax" family
of drivers. It has growing support for the interface cards of hisax
and additionally supports the cool HFCmulti chip based cards.

https://github.com/ISDN4Linux/mISDNuser