Index: channels/chan_dahdi.c
===================================================================
--- channels/chan_dahdi.c	(revision 293886)
+++ channels/chan_dahdi.c	(working copy)
@@ -5132,6 +5132,10 @@
 		ast_log(LOG_WARNING, "Spill already exists?!?\n");
 		ast_free(p->cidspill);
 	}
+
+	/* SAS: Subscriber Alert Signal, 440Hz for 300ms */
+	/* CAS: CPE Alert Signal, 2130Hz * 2750Hz sine waves */
+
 	if (!(p->cidspill = ast_malloc(2400 /* SAS */ + 680 /* CAS */ + READ_SIZE * 4)))
 		return -1;
 	save_conference(p);
@@ -8786,6 +8790,7 @@
 	}
 	/* Expire CID/CW */
 	if (p->cidcwexpire == 1) {
+		p->callwaitcas = 0;
 		ast_verb(3, "CPE does not support Call Waiting Caller*ID.\n");
 		restore_conference(p);
 	}
@@ -8828,8 +8833,13 @@
 
 		f = ast_dsp_process(ast, p->dsp, &p->subs[idx].f);
 
-		/* Check if DSP code thinks we should be muting this frame and mute the conference if so */
-		mute = ast_dsp_was_muted(p->dsp);
+		if (p->callwaitcas) {
+			/* If were in the middle of a SAS+CAS signalling Mute the conference */
+			mute = 1;
+		} else {
+			/* Check if DSP code thinks we should be muting this frame and mute the conference if so */
+			mute = ast_dsp_was_muted(p->dsp);
+		}
 		if (p->muting != mute) {
 			p->muting = mute;
 			dahdi_confmute(p, mute);