Index: channel.c
===================================================================
--- channel.c	(revision 7613)
+++ channel.c	(working copy)
@@ -1778,6 +1778,7 @@
 	struct ast_frame *f = NULL;
 	int blah;
 	int prestate;
+	char *fromwhere = NULL;
 #ifdef ZAPTEL_OPTIMIZATIONS
 	int (*func)(void *);
 	void *data;
@@ -1814,6 +1815,7 @@
 		/* Drop first digit */
 		memmove(chan->dtmfq, chan->dtmfq + 1, sizeof(chan->dtmfq) - 1);
 		ast_mutex_unlock(&chan->lock);
+		ast_log(LOG_NOTICE, "Returning frame from deferred DTMF (chan=%s)\n", chan->name);
 		return &chan->dtmff;
 	}
 	
@@ -1875,22 +1877,25 @@
 		if ((f->frametype == AST_FRAME_CONTROL) && (f->subclass == AST_CONTROL_HANGUP)) {
 			ast_frfree(f);
 			f = NULL;
-		}
+		} else
+			fromwhere = "chan->readq";
 	} else {
 		chan->blocker = pthread_self();
 		if (ast_test_flag(chan, AST_FLAG_EXCEPTION)) {
-			if (chan->tech->exception) 
+			if (chan->tech->exception) {
 				f = chan->tech->exception(chan);
-			else {
+				fromwhere = "chan->tech->exception";
+			} else {
 				ast_log(LOG_WARNING, "Exception flag set on '%s', but no exception handler\n", chan->name);
 				f = &null_frame;
 			}
 			/* Clear the exception flag */
 			ast_clear_flag(chan, AST_FLAG_EXCEPTION);
 		} else {
-			if (chan->tech->read)
+			if (chan->tech->read) {
 				f = chan->tech->read(chan);
-			else
+				fromwhere = "chan->tech->read";
+			} else
 				ast_log(LOG_WARNING, "No read routine on channel %s\n", chan->name);
 		}
 	}
@@ -1994,6 +1999,9 @@
 		chan->fin &= 0x80000000;
 	else
 		chan->fin++;
+	if (fromwhere && f && (f->frametype < 0 || f->frametype > 11)) {
+		ast_log(LOG_WARNING, "Queueing possible bogus frame from %s (chan=%s)\n", fromwhere, chan->name);
+	}
 	ast_mutex_unlock(&chan->lock);
 	return f;
 }