register_appl
ctr->register_appl(ctr, applid, rparam);
register_appl(ctr, applid, &ap->rparam);
register_appl(capi_controller[i], applid, &ap->rparam);
void (*register_appl)(struct capi_ctr *, u16 appl,
session->ctrl.register_appl = cmtp_register_appl;