diff --git a/src/packet/opus.rs b/src/packet/opus.rs
index 365da501..f8763dfd 100644
--- a/src/packet/opus.rs
+++ b/src/packet/opus.rs
@@ -23,8 +23,12 @@ impl Packetizer for OpusPacketizer {
     }
 
     fn is_marker(&mut self, data: &[u8], previous: Option<&[u8]>, last: bool) -> bool {
-        // TODO: dtx
-        false
+        match previous {
+            // silence packets are usually empty with 1-2 bytes header
+            Some(previous) => previous.len() < 2,
+            // first packet can always be considered as start of talk spurt
+            None => true,
+        }
     }
 }