This actually was grabbed mostly from QTISDNLinux.
In addition, you need configuration files, namely /etc/isdn.provider.variables . Replace provider with the name of a provider you are using, e.g. att for AT&T. I provided a sample script. I can use this script and the configuration file to dial my provider with channel bundling.
You must use manual commands on the commandline to dial and hangup, like "isdn.dial provider start" to initialize, and then either "isdn.dial provider single" for one line (you can say "isdn.dial provider addline" later), or two dial two lines immediately, use "isdn.dial provider dual" (you can say "isdn.dial provider remline" later to go back to only one line. To terminate your connection, say "isdn.dial provider hangup". To unload the ISDN stuff say "isdn.dial provider stop".
The above script and configuration file works with my ISDN card, an AVM Fritz PCI. You might need to change the "type", "isdnkort" and "modprobestrength" parameters manually when using a different card. I'm sorry, I can't help you with that. When in trouble, I suggest you use QTISDNLinux.