diff --git a/openbsc/include/openbsc/mgcp_internal.h b/openbsc/include/openbsc/mgcp_internal.h
index 28ea678..9b97165 100644
--- a/openbsc/include/openbsc/mgcp_internal.h
+++ b/openbsc/include/openbsc/mgcp_internal.h
@@ -46,6 +46,7 @@
 	uint32_t last_timestamp;
 	uint32_t err_ts_counter;
 	int32_t last_tsdelta;
+	uint32_t last_arrival_time;
 };
 
 struct mgcp_rtp_state {
diff --git a/openbsc/src/libmgcp/mgcp_network.c b/openbsc/src/libmgcp/mgcp_network.c
index 39d5807..5363fb8 100644
--- a/openbsc/src/libmgcp/mgcp_network.c
+++ b/openbsc/src/libmgcp/mgcp_network.c
@@ -415,10 +415,17 @@
 
 		state->in_stream.ssrc = ssrc;
 		if (rtp_end->force_constant_ssrc) {
-			const int16_t delta_seq = 1;
+			int16_t delta_seq;
 
+			/* Always increment seqno by 1 */
 			state->seq_offset =
-				(state->out_stream.last_seq + delta_seq) - seq;
+				(state->out_stream.last_seq + 1) - seq;
+
+			/* Estimate number of packets that would have been sent */
+			delta_seq =
+				(arrival_time - state->in_stream.last_arrival_time
+				 + state->packet_duration/2) /
+				state->packet_duration;
 
 			adjust_rtp_timestamp_offset(endp, state, rtp_end, addr,
 						    delta_seq, timestamp);
@@ -452,6 +459,7 @@
 	/* Save before patching */
 	state->in_stream.last_timestamp = timestamp;
 	state->in_stream.last_seq = seq;
+	state->in_stream.last_arrival_time = arrival_time;
 
 	if (rtp_end->force_aligned_timing &&
 	    state->out_stream.ssrc == ssrc && state->packet_duration)
diff --git a/openbsc/tests/mgcp/mgcp_test.ok b/openbsc/tests/mgcp/mgcp_test.ok
index 7883574..e383fb5 100644
--- a/openbsc/tests/mgcp/mgcp_test.ok
+++ b/openbsc/tests/mgcp/mgcp_test.ok
@@ -167,14 +167,14 @@
 Out TS change: 160, dTS: 160, Seq change: 1, TS Err change: in +0, out +0
 Stats: Jitter = 27, Transit = 4294967216
 In TS: 160000, dTS: 0, Seq: 1000
-Out TS change: 160, dTS: 160, Seq change: 1, TS Err change: in +0, out +0
-Stats: Jitter = 765, Transit = 11760
+Out TS change: 12000, dTS: 12000, Seq change: 1, TS Err change: in +0, out +0
+Stats: Jitter = 25, Transit = 4294967216
 In TS: 160160, dTS: 160, Seq: 1001
 Out TS change: 160, dTS: 160, Seq change: 1, TS Err change: in +0, out +0
-Stats: Jitter = 718, Transit = 11759
+Stats: Jitter = 24, Transit = 4294967215
 In TS: 160320, dTS: 160, Seq: 1002
 Out TS change: 160, dTS: 160, Seq change: 1, TS Err change: in +0, out +0
-Stats: Jitter = 673, Transit = 11759
+Stats: Jitter = 22, Transit = 4294967215
 Testing packet error detection.
 Output SSRC changed to 11223344
 In TS: 0, dTS: 0, Seq: 0
@@ -447,12 +447,12 @@
 Out TS change: 160, dTS: 160, Seq change: 1, TS Err change: in +0, out +0
 Stats: Jitter = 25, Transit = 4294967136
 In TS: 160000, dTS: 0, Seq: 1000
-Out TS change: 160, dTS: 160, Seq change: 1, TS Err change: in +0, out +0
-Stats: Jitter = 763, Transit = 11680
+Out TS change: 12000, dTS: 12000, Seq change: 1, TS Err change: in +0, out +0
+Stats: Jitter = 23, Transit = 4294967136
 In TS: 160160, dTS: 160, Seq: 1001
 Out TS change: 160, dTS: 160, Seq change: 1, TS Err change: in +0, out +0
-Stats: Jitter = 716, Transit = 11679
+Stats: Jitter = 22, Transit = 4294967135
 In TS: 160320, dTS: 160, Seq: 1002
 Out TS change: 160, dTS: 160, Seq change: 1, TS Err change: in +0, out +0
-Stats: Jitter = 671, Transit = 11679
+Stats: Jitter = 21, Transit = 4294967135
 Done