Question about Dahdi system.conf

Hi, I've been playing with Dahdi and OpenBSC (I have an old T100P card) and something I'm a little confused about is what is the proper configuration for system.conf? Does dahdi itself take care of the hdlc/lapd signalling (in which case I'd expect the signalling channel to be set as dchan in /etc/dahdi/system.conf) or is openbsc taking care of the hdlc/lapd signalling (in which case I'd expect the signalling channel to be set as clear)? Thanks, Gus Bourg