diff --git a/src/nmt/nmt.c b/src/nmt/nmt.c
index 1bd637d..1ab0af0 100644
--- a/src/nmt/nmt.c
+++ b/src/nmt/nmt.c
@@ -924,7 +924,7 @@ static void tx_mo_complete(nmt_t *nmt, frame_t *frame)
 			nmt_new_state(nmt, STATE_ACTIVE);
 			nmt->active_state = ACTIVE_STATE_VOICE;
 			nmt_set_dsp_mode(nmt, DSP_MODE_AUDIO);
-			if (nmt->supervisory) {
+			if (nmt->supervisory && !nmt->dms_call) {
 				super_reset(nmt);
 				timer_start(&nmt->timer, SUPERVISORY_TO1);
 			}
@@ -1179,7 +1179,7 @@ static void tx_mt_complete(nmt_t *nmt, frame_t *frame)
 		nmt_new_state(nmt, STATE_ACTIVE);
 		nmt->active_state = ACTIVE_STATE_VOICE;
 		nmt_set_dsp_mode(nmt, DSP_MODE_AUDIO);
-		if (nmt->supervisory) {
+		if (nmt->supervisory && !nmt->dms_call) {
 			super_reset(nmt);
 			timer_start(&nmt->timer, SUPERVISORY_TO1);
 		}
diff --git a/src/nmt/sms.c b/src/nmt/sms.c
index 2c8d311..d1d2fc6 100644
--- a/src/nmt/sms.c
+++ b/src/nmt/sms.c
@@ -28,6 +28,7 @@
 #include "../common/timer.h"
 #include "nmt.h"
 
+#define SMS_RECEIVE_TO		5.0
 #define SMS_RELEASE_TO		2.0
 
 /* TP-Message-Type-Indicator (TP-MTI) */
@@ -331,6 +332,9 @@ int sms_deliver(nmt_t *nmt, uint8_t ref, const char *orig_address, uint8_t orig_
 	nmt->sms.mt = 1;
 	dms_send(nmt, data, length, 1);
 
+	/* start timer */
+	timer_start(&nmt->sms_timer, SMS_RECEIVE_TO);
+
 	return 0;
 }
 
@@ -596,6 +600,9 @@ void dms_receive(nmt_t *nmt, const uint8_t *data, int length, int __attribute__(
 		sprintf(debug_text + i * 5, " 0x%02x", data[i]);
 	debug_text[length * 5] = '\0';
 
+	/* restart timer */
+	timer_start(&nmt->sms_timer, SMS_RECEIVE_TO);
+
 	PDEBUG(DSMS, DEBUG_DEBUG, "Received %d bytes from DMS layer:%s\n", length, debug_text);
 
 	if (sms->mt && !sms->data_sent) {