diff --git a/README.md b/README.md
index dacec9b07..e1982f6ef 100644
--- a/README.md
+++ b/README.md
@@ -1523,8 +1523,8 @@ Optionally included keys are:
 
 	Used in the `block DTMF` message to select the DTMF blocking mode. The
 	default mode is `drop` which simply drops DTMF event packets. The other
-	supported mode is `silence` which replaces DTMF events with silence
-	audio.
+	supported modes are: `silence` which replaces DTMF events with silence
+	audio; `tone` which replaces DTMF events with a single sine wave tone.
 
 * `delay-buffer`
 
diff --git a/daemon/call_interfaces.c b/daemon/call_interfaces.c
index 0c17c6f67..5900cfb43 100644
--- a/daemon/call_interfaces.c
+++ b/daemon/call_interfaces.c
@@ -1332,6 +1332,9 @@ static void call_ng_main_flags(struct sdp_ng_flags *out, str *key, bencode_item_
 				case CSH_LOOKUP("silence"):
 					out->block_dtmf_mode = BLOCK_DTMF_SILENCE;
 					break;
+				case CSH_LOOKUP("tone"):
+					out->block_dtmf_mode = BLOCK_DTMF_TONE;
+					break;
 				default:
 					ilog(LOG_WARN, "Unknown 'DTMF-security' flag encountered: '" STR_FORMAT "'",
 							STR_FMT(&s));
diff --git a/daemon/codec.c b/daemon/codec.c
index 9039c49c1..50a1e9259 100644
--- a/daemon/codec.c
+++ b/daemon/codec.c
@@ -2386,6 +2386,10 @@ static void delay_frame_manipulate(struct delay_frame *dframe) {
 			case BLOCK_DTMF_SILENCE:
 				memset(frame->extended_data[0], 0, frame->linesize[0]);
 				break;
+			case BLOCK_DTMF_TONE:
+				frame_fill_tone_samples(frame->format, frame->extended_data[0], dframe->ts,
+						frame->nb_samples, 400, 10, frame->sample_rate, frame->channels);
+				break;
 			default:
 				break;
 		}
diff --git a/include/call.h b/include/call.h
index 9de2f8823..39eb53fd2 100644
--- a/include/call.h
+++ b/include/call.h
@@ -205,7 +205,8 @@ enum block_dtmf_mode {
 
 	BLOCK_DTMF___PCM_REPLACE_START = 2,
 	BLOCK_DTMF_SILENCE = 2,
-	BLOCK_DTMF___PCM_REPLACE_END = 2,
+	BLOCK_DTMF_TONE = 3,
+	BLOCK_DTMF___PCM_REPLACE_END = 3,
 };
 
 
diff --git a/lib/codeclib.c b/lib/codeclib.c
index c3757550b..0ef6dc152 100644
--- a/lib/codeclib.c
+++ b/lib/codeclib.c
@@ -2633,3 +2633,26 @@ static int cn_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 		return -1;
 	return 0;
 }
+
+
+void frame_fill_tone_samples(enum AVSampleFormat fmt, void *samples, unsigned int offset, unsigned int num,
+		unsigned int freq, unsigned int volume, unsigned int sample_rate, unsigned int channels)
+{
+	switch (fmt) {
+		case AV_SAMPLE_FMT_S16:
+			tone_samples_int16_t(samples, offset, num, freq, volume, sample_rate, channels);
+			break;
+		case AV_SAMPLE_FMT_S32:
+			tone_samples_int32_t(samples, offset, num, freq, volume, sample_rate, channels);
+			break;
+		case AV_SAMPLE_FMT_DBL:
+			tone_samples_double(samples, offset, num, freq, volume, sample_rate, channels);
+			break;
+		case AV_SAMPLE_FMT_FLT:
+			tone_samples_float(samples, offset, num, freq, volume, sample_rate, channels);
+			break;
+		default:
+			ilog(LOG_ERR | LOG_FLAG_LIMIT, "Unsupported sample format %u", fmt);
+			break;
+	}
+}
diff --git a/lib/codeclib.h b/lib/codeclib.h
index 4ebbe1908..9e6e9459d 100644
--- a/lib/codeclib.h
+++ b/lib/codeclib.h
@@ -341,6 +341,10 @@ void *packet_sequencer_force_next_packet(packet_sequencer_t *ps);
 int packet_sequencer_insert(packet_sequencer_t *ps, seq_packet_t *);
 
 
+void frame_fill_tone_samples(enum AVSampleFormat fmt, void *samples, unsigned int offset, unsigned int num,
+		unsigned int freq, unsigned int volume, unsigned int sample_rate, unsigned int channels);
+
+
 #include "auxlib.h"
 
 
diff --git a/lib/dtmflib.c b/lib/dtmflib.c
index 4b3e91065..02ea025e7 100644
--- a/lib/dtmflib.c
+++ b/lib/dtmflib.c
@@ -209,6 +209,18 @@ freq_samples_x(int32_t, 2147483647.0)
 freq_samples_x(double, 1.0)
 freq_samples_x(float, 1.0)
 
+#define tone_samples_x(type) \
+void tone_samples_ ## type(type *samples, unsigned long offset, unsigned long num, unsigned int freq, \
+		unsigned int volume, unsigned int sample_rate, unsigned int channels) \
+{ \
+	freq_samples_ ## type(samples, offset, num, freq, 0, volume, sample_rate, channels); \
+}
+
+tone_samples_x(int16_t)
+tone_samples_x(int32_t)
+tone_samples_x(double)
+tone_samples_x(float)
+
 void dtmf_samples_int16_t_mono(void *buf, unsigned long offset, unsigned long num, unsigned int event,
 		unsigned int volume, unsigned int sample_rate)
 {
diff --git a/lib/dtmflib.h b/lib/dtmflib.h
index 8c85d9e6c..db0decb46 100644
--- a/lib/dtmflib.h
+++ b/lib/dtmflib.h
@@ -26,4 +26,14 @@ void dtmf_samples_int16_t_mono(void *buf, unsigned long offset, unsigned long nu
 		unsigned int volume, unsigned int sample_rate);
 
 
+void tone_samples_int16_t(int16_t *buf, unsigned long offset, unsigned long num, unsigned int freq,
+		unsigned int volume, unsigned int sample_rate, unsigned int channels);
+void tone_samples_int32_t(int32_t *buf, unsigned long offset, unsigned long num, unsigned int freq,
+		unsigned int volume, unsigned int sample_rate, unsigned int channels);
+void tone_samples_double(double *buf, unsigned long offset, unsigned long num, unsigned int freq,
+		unsigned int volume, unsigned int sample_rate, unsigned int channels);
+void tone_samples_float(float *buf, unsigned long offset, unsigned long num, unsigned int freq,
+		unsigned int volume, unsigned int sample_rate, unsigned int channels);
+
+
 #endif