diff --git a/RelayServer/Endpoints/RtcEndpoints.cs b/RelayServer/Endpoints/RtcEndpoints.cs
index 0d2b5ec..29dba1d 100644
--- a/RelayServer/Endpoints/RtcEndpoints.cs
+++ b/RelayServer/Endpoints/RtcEndpoints.cs
@@ -17,7 +17,7 @@ public static class RtcEndpoints
         {
             await rtcCallService.WriteOfferAsync(request.ChannelId, request.Username, request.SessionDescription);
 
-            RtcNotificationService.Broadcast(new RtcNotificationMessage
+            RtcNotificationService.BroadcastToChannel(new RtcNotificationMessage
             {
                 Type = "rtc_offer_updated",
                 ChannelId = request.ChannelId,
@@ -59,7 +59,7 @@ public static class RtcEndpoints
             //         Sdp = request.Sdp
             //     });
 
-            RtcNotificationService.Broadcast(new RtcNotificationMessage
+            RtcNotificationService.BroadcastToChannel(new RtcNotificationMessage
             {
                 Type = "rtc_answer_updated",
                 ChannelId = request.ChannelId
@@ -93,7 +93,7 @@ public static class RtcEndpoints
                 request.Direction
             );
 
-            RtcNotificationService.Broadcast(new RtcNotificationMessage
+            RtcNotificationService.BroadcastToChannel(new RtcNotificationMessage
             {
                 Type = "rtc_candidate_added",
                 ChannelId = request.ChannelId,
@@ -126,7 +126,7 @@ public static class RtcEndpoints
         {
             await rtcCallService.LeaveCallAsync(request.ChannelId, request.Username);
 
-            RtcNotificationService.Broadcast(new RtcNotificationMessage
+            RtcNotificationService.BroadcastToChannel(new RtcNotificationMessage
             {
                 Type = "rtc_call_left",
                 ChannelId = request.ChannelId,
diff --git a/RelayServer/Services/Chat/ChatSocketBehavior.cs b/RelayServer/Services/Chat/ChatSocketBehavior.cs
index 3d9bfa5..f90afae 100644
--- a/RelayServer/Services/Chat/ChatSocketBehavior.cs
+++ b/RelayServer/Services/Chat/ChatSocketBehavior.cs
@@ -2,6 +2,7 @@
 using RelayServer.Models;
 using RelayServer.Services.Crypto;
 using RelayServer.Services.Data;
+using RelayServer.Services.Rtc;
 using WebSocketSharp;
 using WebSocketSharp.Server;
 
@@ -53,9 +54,31 @@ public class ChatSocketBehavior : WebSocketBehavior
             HandleGetHistory(msg);
             return;
         }
+        
+        if (msg.StartsWith("RTC_JOIN_CHANNEL|"))
+        {
+            HandleRtcJoinChannel(msg);
+            return;
+        }
+
+        if (msg.StartsWith("RTC_LEAVE_CHANNEL|"))
+        {
+            HandleRtcLeaveChannel(msg);
+            return;
+        }
 
         HandleEncryptedChatMessage(msg);
     }
+    
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="e"></param>
+    protected override void OnClose(CloseEventArgs e)
+    {
+        RtcChannelPresenceService.RemoveSession(ID);
+        base.OnClose(e);
+    }
 
     /// <summary>
     /// Extracts a display username from a stored user record id value.
@@ -419,6 +442,10 @@ public class ChatSocketBehavior : WebSocketBehavior
             .GetResult();
     }
     
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <returns></returns>
     private bool EnsureCoreReady()
     {
         if (ClientKeyService is null || Db is null)
@@ -430,6 +457,10 @@ public class ChatSocketBehavior : WebSocketBehavior
         return true;
     }
     
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <returns></returns>
     private bool EnsureCryptoReady()
     {
         if (string.IsNullOrWhiteSpace(ServerPrivateKey) || string.IsNullOrWhiteSpace(ChannelDbKey))
@@ -446,4 +477,50 @@ public class ChatSocketBehavior : WebSocketBehavior
 
         return true;
     }
+    
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="msg"></param>
+    private void HandleRtcJoinChannel(string msg)
+    {
+        var parts = msg.Split('|', 3);
+        if (parts.Length < 3)
+        {
+            Console.WriteLine("Invalid RTC_JOIN_CHANNEL payload.");
+            return;
+        }
+
+        var username = parts[1];
+        var channelId = parts[2];
+
+        RtcChannelPresenceService.SetUser(ID, username);
+        RtcChannelPresenceService.JoinChannel(ID, channelId);
+
+        Console.WriteLine($"RTC presence joined: session={ID}, user={username}, channel={channelId}");
+    }
+
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="msg"></param>
+    private void HandleRtcLeaveChannel(string msg)
+    {
+        var parts = msg.Split('|', 3);
+        if (parts.Length < 3)
+        {
+            Console.WriteLine("Invalid RTC_LEAVE_CHANNEL payload.");
+            return;
+        }
+
+        var username = parts[1];
+        var channelId = parts[2];
+
+        if (RtcChannelPresenceService.IsInChannel(ID, channelId))
+        {
+            RtcChannelPresenceService.LeaveChannel(ID);
+        }
+
+        Console.WriteLine($"RTC presence left: session={ID}, user={username}, channel={channelId}");
+    }
 }
\ No newline at end of file
diff --git a/RelayServer/Services/Rtc/RtcChannelPresenceService.cs b/RelayServer/Services/Rtc/RtcChannelPresenceService.cs
new file mode 100644
index 0000000..581f5b7
--- /dev/null
+++ b/RelayServer/Services/Rtc/RtcChannelPresenceService.cs
@@ -0,0 +1,55 @@
+using System.Collections.Concurrent;
+
+namespace RelayServer.Services.Rtc;
+
+public static class RtcChannelPresenceService
+{
+    private static readonly ConcurrentDictionary<string, string> SessionToChannel = new();
+    private static readonly ConcurrentDictionary<string, string> SessionToUsername = new();
+
+    public static void SetUser(string sessionId, string username)
+    {
+        SessionToUsername[sessionId] = username;
+    }
+
+    public static void JoinChannel(string sessionId, string channelId)
+    {
+        SessionToChannel[sessionId] = channelId;
+    }
+
+    public static void LeaveChannel(string sessionId)
+    {
+        SessionToChannel.TryRemove(sessionId, out _);
+    }
+
+    public static void RemoveSession(string sessionId)
+    {
+        SessionToChannel.TryRemove(sessionId, out _);
+        SessionToUsername.TryRemove(sessionId, out _);
+    }
+
+    public static IReadOnlyList<string> GetSessionsInChannel(string channelId)
+    {
+        return SessionToChannel
+            .Where(x => x.Value == channelId)
+            .Select(x => x.Key)
+            .ToList();
+    }
+
+    public static IReadOnlyList<string> GetUsersInChannel(string channelId)
+    {
+        var sessionIds = GetSessionsInChannel(channelId);
+
+        return sessionIds
+            .Where(id => SessionToUsername.ContainsKey(id))
+            .Select(id => SessionToUsername[id])
+            .Distinct(StringComparer.OrdinalIgnoreCase)
+            .ToList();
+    }
+
+    public static bool IsInChannel(string sessionId, string channelId)
+    {
+        return SessionToChannel.TryGetValue(sessionId, out var currentChannel) &&
+               string.Equals(currentChannel, channelId, StringComparison.Ordinal);
+    }
+}
\ No newline at end of file
diff --git a/RelayServer/Services/Rtc/RtcNotificationService.cs b/RelayServer/Services/Rtc/RtcNotificationService.cs
index 5c4f209..9968d74 100644
--- a/RelayServer/Services/Rtc/RtcNotificationService.cs
+++ b/RelayServer/Services/Rtc/RtcNotificationService.cs
@@ -8,12 +8,21 @@ public static class RtcNotificationService
 {
     public static WebSocketServer? Server { get; set; }
 
-    public static void Broadcast(RtcNotificationMessage message)
+    public static void BroadcastToChannel(RtcNotificationMessage message)
     {
         if (Server is null)
             return;
 
+        var host = Server.WebSocketServices["/"];
+        if (host is null)
+            return;
+
         var json = JsonSerializer.Serialize(message);
-        Server.WebSocketServices["/"]?.Sessions.Broadcast(json);
+        var sessionIds = RtcChannelPresenceService.GetSessionsInChannel(message.ChannelId);
+
+        foreach (var sessionId in sessionIds)
+        {
+            host.Sessions.SendTo(json, sessionId);
+        }
     }
 }
\ No newline at end of file