diff --git a/include/osmocom/mgcp/mgcp_network.h b/include/osmocom/mgcp/mgcp_network.h
index 75b342d..d6d90dd 100644
--- a/include/osmocom/mgcp/mgcp_network.h
+++ b/include/osmocom/mgcp/mgcp_network.h
@@ -176,4 +176,4 @@
 /* internal RTP Annex A counting */
 void mgcp_rtp_annex_count(const struct mgcp_endpoint *endp, struct mgcp_rtp_state *state,
 			const uint16_t seq, const int32_t transit,
-			const uint32_t ssrc);
+			const uint32_t ssrc, const bool marker_bit);
diff --git a/src/libosmo-mgcp/mgcp_network.c b/src/libosmo-mgcp/mgcp_network.c
index d18c7cb..82dc6ec 100644
--- a/src/libosmo-mgcp/mgcp_network.c
+++ b/src/libosmo-mgcp/mgcp_network.c
@@ -285,13 +285,21 @@
 				       struct mgcp_rtp_state *state,
 				       const struct mgcp_rtp_end *rtp_end,
 				       const struct osmo_sockaddr *addr,
-				       int16_t delta_seq, uint32_t in_timestamp)
+				       int16_t delta_seq, uint32_t in_timestamp,
+				       bool marker_bit)
 {
 	int32_t tsdelta = state->packet_duration;
 	int timestamp_offset;
 	uint32_t out_timestamp;
 	char ipbuf[INET6_ADDRSTRLEN];
 
+	if (marker_bit) {
+		/* If RTP pkt contains marker bit, the timestamps are not longer
+		 * in sync, so we can erase timestamp offset patching. */
+		state->patch.timestamp_offset = 0;
+		return 0;
+	}
+
 	if (tsdelta == 0) {
 		tsdelta = state->out_stream.last_tsdelta;
 		if (tsdelta != 0) {
@@ -335,13 +343,19 @@
 				      struct mgcp_rtp_state *state,
 				      const struct mgcp_rtp_end *rtp_end,
 				      const struct osmo_sockaddr *addr,
-				      uint32_t timestamp)
+				      uint32_t timestamp, bool marker_bit)
 {
 	char ipbuf[INET6_ADDRSTRLEN];
 	int ts_error = 0;
 	int ts_check = 0;
 	int ptime = state->packet_duration;
 
+	if (marker_bit) {
+		/* If RTP pkt contains marker bit, the timestamps are not longer
+		 * in sync, so no alignment is needed. */
+		return 0;
+	}
+
 	/* Align according to: T + Toffs - Tlast = k * Tptime */
 
 	ts_error = ts_alignment_error(&state->out_stream, ptime,
@@ -414,12 +428,13 @@
 
 void mgcp_rtp_annex_count(const struct mgcp_endpoint *endp,
 			  struct mgcp_rtp_state *state, const uint16_t seq,
-			  const int32_t transit, const uint32_t ssrc)
+			  const int32_t transit, const uint32_t ssrc,
+			  const bool marker_bit)
 {
 	int32_t d;
 
 	/* initialize or re-initialize */
-	if (!state->stats.initialized || state->stats.ssrc != ssrc) {
+	if (!state->stats.initialized || state->stats.ssrc != ssrc || marker_bit) {
 		state->stats.initialized = 1;
 		state->stats.base_seq = seq;
 		state->stats.max_seq = seq - 1;
@@ -503,6 +518,7 @@
 	int32_t transit;
 	uint16_t seq;
 	uint32_t timestamp, ssrc;
+	bool marker_bit;
 	struct rtp_hdr *rtp_hdr;
 	int payload = rtp_end->codec->payload_type;
 	unsigned int len = msgb_length(msg);
@@ -515,9 +531,10 @@
 	timestamp = ntohl(rtp_hdr->timestamp);
 	arrival_time = get_current_ts(rtp_end->codec->rate);
 	ssrc = ntohl(rtp_hdr->ssrc);
+	marker_bit = !!rtp_hdr->marker;
 	transit = arrival_time - timestamp;
 
-	mgcp_rtp_annex_count(endp, state, seq, transit, ssrc);
+	mgcp_rtp_annex_count(endp, state, seq, transit, ssrc, marker_bit);
 
 	if (!state->initialized) {
 		state->initialized = 1;
@@ -571,7 +588,7 @@
 			    state->packet_duration;
 
 			adjust_rtp_timestamp_offset(endp, state, rtp_end, addr,
-						    delta_seq, timestamp);
+						    delta_seq, timestamp, marker_bit);
 
 			state->patch.patch_ssrc = true;
 			ssrc = state->patch.orig_ssrc;
@@ -589,10 +606,14 @@
 
 		state->in_stream.last_tsdelta = 0;
 	} else {
-		/* Compute current per-packet timestamp delta */
-		check_rtp_timestamp(endp, state, &state->in_stream, rtp_end,
-				    addr, seq, timestamp, "input",
-				    &state->in_stream.last_tsdelta);
+		if (!marker_bit) {
+			/* Compute current per-packet timestamp delta */
+			check_rtp_timestamp(endp, state, &state->in_stream, rtp_end,
+					    addr, seq, timestamp, "input",
+					    &state->in_stream.last_tsdelta);
+		} else {
+			state->in_stream.last_tsdelta = 0;
+		}
 
 		if (state->patch.patch_ssrc)
 			ssrc = state->patch.orig_ssrc;
@@ -607,7 +628,7 @@
 	    state->out_stream.ssrc == ssrc && state->packet_duration)
 		/* Align the timestamp offset */
 		align_rtp_timestamp_offset(endp, state, rtp_end, addr,
-					   timestamp);
+					   timestamp, marker_bit);
 
 	/* Store the updated SSRC back to the packet */
 	if (state->patch.patch_ssrc)
@@ -622,10 +643,14 @@
 	rtp_hdr->timestamp = htonl(timestamp);
 
 	/* Check again, whether the timestamps are still valid */
-	if (state->out_stream.ssrc == ssrc)
-		check_rtp_timestamp(endp, state, &state->out_stream, rtp_end,
-				    addr, seq, timestamp, "output",
-				    &state->out_stream.last_tsdelta);
+	if (!marker_bit) {
+		if (state->out_stream.ssrc == ssrc)
+			check_rtp_timestamp(endp, state, &state->out_stream, rtp_end,
+					    addr, seq, timestamp, "output",
+					    &state->out_stream.last_tsdelta);
+	} else {
+		state->out_stream.last_tsdelta = 0;
+	}
 
 	/* Save output values */
 	state->out_stream.last_seq = seq;
diff --git a/tests/mgcp/mgcp_test.c b/tests/mgcp/mgcp_test.c
index 6978b1d..7397f5c 100644
--- a/tests/mgcp/mgcp_test.c
+++ b/tests/mgcp/mgcp_test.c
@@ -1282,6 +1282,15 @@
 	/* RTP: SeqNo=1002, TS=160320 */
 	{2.040000, 20, "\x80\x62\x03\xEA\x00\x02\x72\x40\x50\x60\x70\x80"
 	 "\x01\x23\x45\x67\x89\xAB\xCD\xEF"},
+	/* RTP: SeqNo=1003, TS=180320, Marker */
+	{2.060000, 20, "\x80\xE2\x03\xEB\x00\x02\xC0\x60\x50\x60\x70\x80"
+	 "\x01\x23\x45\x67\x89\xAB\xCD\xEF"},
+	 /* RTP: SeqNo=1004, TS=180480 */
+	{2.080000, 20, "\x80\x62\x03\xEC\x00\x02\xC1\x00\x50\x60\x70\x80"
+	 "\x01\x23\x45\x67\x89\xAB\xCD\xEF"},
+	 /* RTP: SeqNo=1005, TS=180480, 10ms too late */
+	{2.110000, 20, "\x80\x62\x03\xED\x00\x02\xC1\xA0\x50\x60\x70\x80"
+	 "\x01\x23\x45\x67\x89\xAB\xCD\xEF"},
 };
 
 static void test_packet_error_detection(int patch_ssrc, int patch_ts)
@@ -1566,24 +1575,24 @@
 
 	OSMO_ASSERT(conn->state.stats.initialized == 0);
 
-	mgcp_rtp_annex_count(endp, &conn->state, 0, 0, 2342);
+	mgcp_rtp_annex_count(endp, &conn->state, 0, 0, 2342, false);
 	OSMO_ASSERT(conn->state.stats.initialized == 1);
 	OSMO_ASSERT(conn->state.stats.cycles == 0);
 	OSMO_ASSERT(conn->state.stats.max_seq == 0);
 
-	mgcp_rtp_annex_count(endp, &conn->state, 1, 0, 2342);
+	mgcp_rtp_annex_count(endp, &conn->state, 1, 0, 2342, false);
 	OSMO_ASSERT(conn->state.stats.initialized == 1);
 	OSMO_ASSERT(conn->state.stats.cycles == 0);
 	OSMO_ASSERT(conn->state.stats.max_seq == 1);
 
 	/* now jump.. */
-	mgcp_rtp_annex_count(endp, &conn->state, UINT16_MAX, 0, 2342);
+	mgcp_rtp_annex_count(endp, &conn->state, UINT16_MAX, 0, 2342, false);
 	OSMO_ASSERT(conn->state.stats.initialized == 1);
 	OSMO_ASSERT(conn->state.stats.cycles == 0);
 	OSMO_ASSERT(conn->state.stats.max_seq == UINT16_MAX);
 
 	/* and wrap */
-	mgcp_rtp_annex_count(endp, &conn->state, 0, 0, 2342);
+	mgcp_rtp_annex_count(endp, &conn->state, 0, 0, 2342, false);
 	OSMO_ASSERT(conn->state.stats.initialized == 1);
 	OSMO_ASSERT(conn->state.stats.cycles == UINT16_MAX + 1);
 	OSMO_ASSERT(conn->state.stats.max_seq == 0);
diff --git a/tests/mgcp/mgcp_test.ok b/tests/mgcp/mgcp_test.ok
index 575fd83..94fada3 100644
--- a/tests/mgcp/mgcp_test.ok
+++ b/tests/mgcp/mgcp_test.ok
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