mISDN is the latest incarnation of a Linux in-kernel ISDN stack.
You can find more information about mISDN at http://www.misdn.org/
The OpenBSC project uses mISDN as a foundation
- to drive the HFC-E1 card, using the hfcmulti.ko driver
- to handle the TEI assignment procedures on the Abis interface
- to offer a sockets based kernel/userspace interface for the actual BSC code
Unfortunately, there are a number of subtle differences between Q.921 and the way how Abis utilizes the E1 physical link, and as a result mISDN could not be used unmodified to drive Abis. We have developed some patches that eventually were merged into the mISDN project. Starting from kernel 2.6.30, you do no longer need to patch it to support the A-bis layer2. SDN mainline.
please make sure to load the hfcmulti Linux kernel module using the option "dslot=1" parameter. If you fail to do so, the timeslot for signalling will be 15 (whereas the BTS uses 1).