diff -urN linux-2.4.20-clean/drivers/isdn/isdn_net.c linux-2.4.20/drivers/isdn/isdn_net.c
--- linux-2.4.20-clean/drivers/isdn/isdn_net.c	2002-11-29 00:53:13.000000000 +0100
+++ linux-2.4.20/drivers/isdn/isdn_net.c	2003-03-14 18:37:05.000000000 +0100
@@ -2831,6 +2831,7 @@
 
 			/* If binding is exclusive, try to grab the channel */
 			save_flags(flags);
+			cli();
 			if ((i = isdn_get_free_channel(ISDN_USAGE_NET,
 				lp->l2_proto, lp->l3_proto, drvidx,
 				chidx, lp->msn)) < 0) {