28. misc: Miscellaneous

28.1 misc_standards: Which standards apply to the ISDN protocol layers?

These are the main standards:

• Layer 1: ITU I.430 and ETSI 300 012-1
• Layer 2: ITU Q.921 and ETSI 300 125-1
• Layer 3: ITU Q.931 and ETSI 300 102-1 (plus some changes and clarifications in ETSI 300 403)

28.2 misc_nonullcable: Can I connect two ISDN devices directly with a kind of "null modem cable"?

This is only possible if one of the cable can run in NT mode (see glossary on what this is: glossary_ntmode). Only a few cards allow it, all others need an NTBA or PBX with an internal bus to communicate with each other. See question feature_crossedcable.

28.3 misc_uisdn: Can isdn4linux run in parallel to UISDN?

Yes. Both ISDN packages load the module isdn.o, otherwise the naming conventions are different. Tip: rename Urlichs isdn.o to uisdn.o, and change lib/modules/modules.isdn (or whatever the file is called that lists the modules and is read by the script) accordingly. Happily the default names of the ISDN devices are also different.