Linux Looks To Orphan Its ISDN Subsystem

Written by Michael Larabel in Linux Networking on 23 October 2025 at 06:09 AM EDT. 26 Comments

Integrated Services Digital Network (ISDN) usage is long obsolete even where it had enjoyed some successes in the likes of Germany and Norway. With no activity in years to the ISDN and mISDN subsystem code for the Linux kernel, a patch was sent out today for orphaning the code.

Bagas Sanjaya posted the patch to the mailing list today that would make the ISDN/mISDN subsystem and ISDN/CMTP over Bluetooth code orphaned within the Linux kernel. The rationale for orphaning the ISDN Linux code amounts to no activity in years from its listed maintainer nor any other signs of ongoing activity:

"We have not heard any activities from Karsten in years:

- Last review tag was nine years ago in commit a921e9bd4e22a7 ("isdn: i4l: move active-isdn drivers to staging")
- Last message on lore was in October 2020.

Furthermore, messages to isdn mailing list bounce.

Mark the subsystem as orphan to reflect these."

So for now the patch makes the ISDN code orphaned but stops short of removing it at this point in time, which could come down the line if no one expresses objections or commits to maintaining it.

👁 ISDN orphaned

The mISDN in this context is for modular ISDN drivers.