diff --git a/src/packet/mod.rs b/src/packet/mod.rs
index 768fbca6..a650f6ce 100644
--- a/src/packet/mod.rs
+++ b/src/packet/mod.rs
@@ -209,7 +209,7 @@ pub(crate) enum CodecDepacketizer {
 impl From<Codec> for CodecPacketizer {
     fn from(c: Codec) -> Self {
         match c {
-            Codec::Opus => CodecPacketizer::Opus(OpusPacketizer),
+            Codec::Opus => CodecPacketizer::Opus(OpusPacketizer::default()),
             Codec::H264 => CodecPacketizer::H264(H264Packetizer::default()),
             Codec::H265 => unimplemented!("Missing packetizer for H265"),
             Codec::Vp8 => CodecPacketizer::Vp8(Vp8Packetizer::default()),
diff --git a/src/packet/opus.rs b/src/packet/opus.rs
index 365da501..d6628e6a 100644
--- a/src/packet/opus.rs
+++ b/src/packet/opus.rs
@@ -2,7 +2,10 @@ use super::{CodecExtra, Depacketizer, MediaKind, PacketError, Packetizer};
 
 /// Packetizes Opus RTP packets.
 #[derive(Default, Debug, Copy, Clone)]
-pub struct OpusPacketizer;
+pub struct OpusPacketizer {
+    // stores if a marker was previously set
+    marker: bool,
+}
 
 impl Packetizer for OpusPacketizer {
     fn packetize(&mut self, mtu: usize, payload: &[u8]) -> Result<Vec<Vec<u8>>, PacketError> {
@@ -23,8 +26,23 @@ impl Packetizer for OpusPacketizer {
     }
 
     fn is_marker(&mut self, data: &[u8], previous: Option<&[u8]>, last: bool) -> bool {
-        // TODO: dtx
-        false
+        // any non silenced packet would generally have more than 2 byts
+        let mut is_marker = data.len() > 2;
+
+        match self.marker {
+            true => {
+                if !is_marker {
+                    self.marker = false;
+                }
+                is_marker = false;
+            }
+            false => {
+                if is_marker {
+                    self.marker = true;
+                }
+            }
+        }
+        is_marker
     }
 }
 
@@ -84,7 +102,7 @@ mod test {
 
     #[test]
     fn test_opus_payload() -> Result<(), PacketError> {
-        let mut pck = OpusPacketizer;
+        let mut pck = OpusPacketizer::default();
         let empty = &[];
         let payload = &[0x90, 0x90, 0x90];
 
diff --git a/tests/rtp_to_frame.rs b/tests/talk_start_spurt.rs
similarity index 53%
rename from tests/rtp_to_frame.rs
rename to tests/talk_start_spurt.rs
index 62f3af14..0c52b1e8 100644
--- a/tests/rtp_to_frame.rs
+++ b/tests/talk_start_spurt.rs
@@ -2,7 +2,7 @@ use std::collections::VecDeque;
 use std::time::Duration;
 
 use str0m::format::Codec;
-use str0m::media::MediaKind;
+use str0m::media::{Frequency, MediaKind, MediaTime};
 use str0m::rtp::{ExtensionValues, Ssrc};
 use str0m::{Event, Rtc, RtcError};
 
@@ -10,7 +10,7 @@ mod common;
 use common::{connect_l_r_with_rtc, init_log, progress};
 
 #[test]
-pub fn audio_start_of_talk_spurt() -> Result<(), RtcError> {
+pub fn audio_start_of_talk_spurt_frame() -> Result<(), RtcError> {
     init_log();
 
     let rtc1 = Rtc::builder().set_rtp_mode(true).build();
@@ -108,3 +108,103 @@ pub fn audio_start_of_talk_spurt() -> Result<(), RtcError> {
 
     Ok(())
 }
+
+#[test]
+pub fn audio_start_of_talk_spurt_rtp() -> Result<(), RtcError> {
+    init_log();
+
+    let rtc1 = Rtc::builder().build();
+    let rtc2 = Rtc::builder()
+        .set_reordering_size_audio(0)
+        .set_rtp_mode(true)
+        .build();
+
+    let (mut l, mut r) = connect_l_r_with_rtc(rtc1, rtc2);
+
+    let mid = "audio".into();
+    let ssrc_tx: Ssrc = 1337.into();
+
+    l.direct_api().declare_media(mid, MediaKind::Audio);
+    l.direct_api().declare_stream_tx(ssrc_tx, None, mid, None);
+    r.direct_api().declare_media(mid, MediaKind::Audio);
+
+    let max = l.last.max(r.last);
+    l.last = max;
+    r.last = max;
+
+    let params = l.params_opus();
+
+    assert_eq!(params.spec().codec, Codec::Opus);
+    let pt = params.pt();
+
+    let to_write: Vec<&[u8]> = vec![
+        // 1
+        &[0x1],
+        // 2
+        &[0x1, 0x2, 0x3, 0x4],
+        // 4
+        &[0x9, 0xa, 0xb, 0xc],
+        // 3
+        &[0x5, 0x6, 0x7, 0x8],
+        // 5
+        &[0x1],
+        // 6
+        &[0x9, 0xa, 0xb, 0xc],
+    ];
+
+    let mut to_write: VecDeque<_> = to_write.into();
+
+    let mut write_at = l.last + Duration::from_millis(300);
+
+    let mut counts: Vec<u64> = vec![0, 1, 2, 4, 3, 5, 6];
+
+    loop {
+        if l.start + l.duration() > write_at {
+            write_at = l.last + Duration::from_millis(300);
+            if let Some(packet) = to_write.pop_front() {
+                let wallclock = l.start + l.duration();
+
+                let count = counts.remove(0);
+                let time = count * 1000 + 47_000_000;
+
+                l.writer(mid)
+                    .unwrap()
+                    .write(
+                        pt,
+                        wallclock,
+                        MediaTime::new(time, Frequency::FORTY_EIGHT_KHZ),
+                        packet.to_vec(),
+                    )
+                    .unwrap();
+            }
+        }
+
+        progress(&mut l, &mut r)?;
+
+        if l.duration() > Duration::from_secs(10) {
+            break;
+        }
+    }
+
+    let rtp_packets: Vec<_> = r
+        .events
+        .iter()
+        .filter_map(|(_, e)| {
+            if let Event::RtpPacket(p) = e {
+                Some(p)
+            } else {
+                None
+            }
+        })
+        .collect();
+
+    assert_eq!(rtp_packets.len(), 6);
+    let is_marker = [false, true, false, false, false, true];
+
+    rtp_packets
+        .iter()
+        .enumerate()
+        .for_each(|(i, r)| assert_eq!(r.header.marker, is_marker[i]));
+
+    Ok(())
+}