From 136e7e32e61b71f0de98f5f150fc585a29391a47 Mon Sep 17 00:00:00 2001
From: Aaron Clauson <aaron@sipsorcery.com>
Date: Fri, 12 Jun 2026 19:40:58 +0100
Subject: [PATCH] Fixed bug not setting initial seqnum for rtp media stream.

---
 src/SIPSorcery/net/RTP/Streams/MediaStream.cs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/SIPSorcery/net/RTP/Streams/MediaStream.cs b/src/SIPSorcery/net/RTP/Streams/MediaStream.cs
index 46a667a1d..f30684e72 100644
--- a/src/SIPSorcery/net/RTP/Streams/MediaStream.cs
+++ b/src/SIPSorcery/net/RTP/Streams/MediaStream.cs
@@ -818,6 +818,13 @@ public void OnReceiveRTPPacket(RTPHeader hdr, int localPort, IPEndPoint remoteEn
                 }
                 else
                 {
+                    if (RemoteTrack != null)
+                    {
+                        // Must be updated for LogIfWrongSeqNumber to function: with the initial
+                        // value of 0 the sequence discontinuity check never fires, so the
+                        // unbuffered path previously never reported out of order packets.
+                        RemoteTrack.LastRemoteSeqNum = rtpPacket.Header.SequenceNumber;
+                    }
                     ProcessRtpPacket(remoteEndPoint, rtpPacket, format.Value);
                 }