diff --git a/README.md b/README.md
index 3e46a028d..75d2e38dd 100644
--- a/README.md
+++ b/README.md
@@ -502,6 +502,9 @@ key-value pair), it can be escaped by using two dashes instead, e.g.
 
 The default (highest) bitrates for AMR and AMR-WB are 6700 and 14250, respectively.
 
+If a Codec Mode Request (CMR) is received from the AMR peer, then *rtpengine* will adhere to the request
+and switch encoder bitrate unconditionally, even if it's a higher bitrate than originally desired.
+
 Call recording
 ==============
 
diff --git a/daemon/codec.c b/daemon/codec.c
index d491d4cec..ed1b14195 100644
--- a/daemon/codec.c
+++ b/daemon/codec.c
@@ -1723,6 +1723,19 @@ uint64_t codec_decoder_unskip_pts(struct codec_ssrc_handler *ch) {
 }
 
 static int codec_decoder_event(enum codec_event event, void *ptr, void *data) {
+	struct call_media *media = data;
+	if (!media)
+		return 0;
+
+	switch (event) {
+		case CE_AMR_CMR_RECV:
+			// ignore locking and races for this
+			media->u.amr.cmr.cmr_in = GPOINTER_TO_UINT(ptr);
+			media->u.amr.cmr.cmr_in_ts = rtpe_now;
+			break;
+		default:
+			break;
+	}
 	return 0;
 }
 
@@ -1985,6 +1998,10 @@ static int packet_decoded_common(decoder_t *decoder, AVFrame *frame, void *u1, v
 
 	__dtmf_detect(ch, frame);
 
+	// locking deliberately ignored
+	if (mp->media_out)
+		ch->encoder->codec_options.amr.cmr = mp->media_out->u.amr.cmr;
+
 	input_func(ch->encoder, frame, h->packet_encoded, ch, mp);
 
 discard:
diff --git a/include/call.h b/include/call.h
index 01cfc0da0..c4c18d191 100644
--- a/include/call.h
+++ b/include/call.h
@@ -336,6 +336,13 @@ struct call_media {
 	struct codec_handler	*dtmf_injector;
 	struct t38_gateway	*t38_gateway;
 	struct codec_handler	*t38_handler;
+#ifdef WITH_TRANSCODING
+	union {
+		struct {
+			struct amr_cmr cmr;
+		} amr;
+	} u;
+#endif
 
 	int			ptime; // either from SDP or overridden
 
diff --git a/lib/codeclib.c b/lib/codeclib.c
index 095c5fe5f..0a2f57732 100644
--- a/lib/codeclib.c
+++ b/lib/codeclib.c
@@ -57,6 +57,7 @@ static int avc_encoder_input(encoder_t *enc, AVFrame **frame);
 static void avc_encoder_close(encoder_t *enc);
 
 static int amr_decoder_input(decoder_t *dec, const str *data, GQueue *out);
+static void amr_encoder_got_packet(encoder_t *enc);
 static int ilbc_decoder_input(decoder_t *dec, const str *data, GQueue *out);
 
 static const char *dtmf_decoder_init(decoder_t *, const str *);
@@ -90,6 +91,7 @@ static const codec_type_t codec_type_amr = {
 	.decoder_close = avc_decoder_close,
 	.encoder_init = avc_encoder_init,
 	.encoder_input = avc_encoder_input,
+	.encoder_got_packet = amr_encoder_got_packet,
 	.encoder_close = avc_encoder_close,
 };
 static const codec_type_t codec_type_dtmf = {
@@ -1234,10 +1236,11 @@ int encoder_input_data(encoder_t *enc, AVFrame *frame,
 			return -1;
 
 		if (enc->avpkt.size) {
-			//av_write_frame(output->fmtctx, &output->avpkt);
+			if (enc->def->codec_type->encoder_got_packet)
+				enc->def->codec_type->encoder_got_packet(enc);
+
 			callback(enc, u1, u2);
 
-			//output->fifo_pts += output->frame->nb_samples;
 			enc->mux_dts = enc->avpkt.dts + 1; // min next expected dts
 
 			av_packet_unref(&enc->avpkt);
@@ -1645,7 +1648,10 @@ static int amr_decoder_input(decoder_t *dec, const str *data, GQueue *out) {
 	err = "no CMR";
 	if (bitstr_shift_ret(&d, 4, &cmr))
 		goto err;
-	// XXX handle CMR?
+
+	unsigned int cmr_int = cmr_chr[0] >> 4;
+	if (cmr_int != 15)
+		decoder_event(dec, CE_AMR_CMR_RECV, GUINT_TO_POINTER(cmr_int));
 
 	if (dec->codec_options.amr.octet_aligned) {
 		if (bitstr_shift(&d, 4))
@@ -1746,6 +1752,24 @@ err:
 
 	return -1;
 }
+static void amr_encoder_mode_change(encoder_t *enc) {
+	if (!memcmp(&enc->codec_options.amr.cmr.cmr_in_ts,
+				&enc->u.avc.u.amr.cmr_in_ts, sizeof(struct timeval)))
+		return;
+	unsigned int cmr = enc->codec_options.amr.cmr.cmr_in;
+	if (cmr >= AMR_FT_TYPES)
+		return;
+	// ignore CMR for invalid modes
+	if (enc->codec_options.amr.mode_set && !(enc->codec_options.amr.mode_set & (1 << cmr)))
+		return;
+	int req_br = enc->codec_options.amr.bitrates[cmr];
+	if (!req_br)
+		return;
+	enc->u.avc.avcctx->bit_rate = req_br;
+}
+static void amr_encoder_got_packet(encoder_t *enc) {
+	amr_encoder_mode_change(enc);
+}
 static int packetizer_amr(AVPacket *pkt, GString *buf, str *output, encoder_t *enc) {
 	assert(pkt->size >= 1);
 
diff --git a/lib/codeclib.h b/lib/codeclib.h
index 2b5ee3e2f..fa8479319 100644
--- a/lib/codeclib.h
+++ b/lib/codeclib.h
@@ -81,9 +81,15 @@ struct codec_type_s {
 
 	const char *(*encoder_init)(encoder_t *, const str *);
 	int (*encoder_input)(encoder_t *, AVFrame **);
+	void (*encoder_got_packet)(encoder_t *);
 	void (*encoder_close)(encoder_t *);
 };
 
+struct amr_cmr {
+	struct timeval cmr_in_ts;
+	unsigned int cmr_in;
+};
+
 union codec_options_u {
 	struct {
 		int interleaving;
@@ -94,6 +100,8 @@ union codec_options_u {
 
 		const unsigned int *bits_per_frame;
 		const unsigned int *bitrates;
+
+		struct amr_cmr cmr; // input from external calling code
 	} amr;
 };
 
@@ -145,7 +153,7 @@ struct resample_s {
 };
 
 enum codec_event {
-	CE_DUMMY = -1,
+	CE_AMR_CMR_RECV,
 };
 
 struct decoder_s {
@@ -191,6 +199,12 @@ struct encoder_s {
 		struct {
 			AVCodec *codec;
 			AVCodecContext *avcctx;
+
+			union {
+				struct {
+					struct timeval cmr_in_ts; // used internally
+				} amr;
+			} u;
 		} avc;
 #ifdef HAVE_BCG729
 		bcg729EncoderChannelContextStruct *bcg729;