Index: channels/chan_unistim.c
===================================================================
--- channels/chan_unistim.c	(revision 189272)
+++ channels/chan_unistim.c	(working copy)
@@ -2468,7 +2468,7 @@
 	struct ast_frame f = { 0, };
 	struct unistim_subchannel *sub;
 	sub = pte->device->lines->subs[SUB_REAL];
-	if (!sub->owner) {
+	if (!sub->owner || sub->alreadygone) {
 		ast_log(LOG_WARNING, "Unable to find subchannel in dtmf senddigit\n");
 		return -1;
 	}
@@ -4218,8 +4218,8 @@
 
 	sub = pte->device->lines->subs[SUB_REAL];
 
-	if (!sub->owner) {
-		ast_log(LOG_WARNING, "Unable to find subchannel in dtmf senddigiti_end\n");
+	if (!sub->owner || sub->alreadygone) {
+		ast_log(LOG_WARNING, "Unable to find subchannel in dtmf senddigit_end\n");
 		return -1;
 	}