diff --git a/src/protocol.cpp b/src/protocol.cpp
index 64adce49..01847328 100755
--- a/src/protocol.cpp
+++ b/src/protocol.cpp
@@ -154,6 +154,7 @@ MESSAGES (with connection)
     - "audiocod type":   audio coding type, the following types are supported:
                           - 0: none, no audio coding applied
                           - 1: CELT
+                          - 2: OPUS
     - "version":         version of the audio coder, if not used this value
                          shall be set to 0
     - "audiocod arg":    argument for the audio coder, if not used this value
@@ -165,6 +166,11 @@ MESSAGES (with connection)
     note: does not have any data -> n = 0
 
 
+// #### COMPATIBILITY OLD VERSION, TO BE REMOVED ####
+- PROTMESSID_OPUS_SUPPORTED: Informs that OPUS codec is supported
+
+    note: does not have any data -> n = 0
+
 
 CONNECTION LESS MESSAGES
 ------------------------
@@ -572,6 +578,11 @@ case PROTMESSID_PING_MS:
                 case PROTMESSID_REQ_NETW_TRANSPORT_PROPS:
                     bRet = EvaluateReqNetwTranspPropsMes();
                     break;
+
+// #### COMPATIBILITY OLD VERSION, TO BE REMOVED ####
+case PROTMESSID_OPUS_SUPPORTED:
+    bRet = EvaluateOpusSupportedMes();
+    break;
                 }
 
                 // immediately send acknowledge message
@@ -1337,7 +1348,8 @@ bool CProtocol::EvaluateNetwTranspPropsMes ( const CVector<uint8_t>& vecData )
         static_cast<int> ( GetValFromStream ( vecData, iPos, 2 ) );
 
     if ( ( iRecCodingType != CT_NONE ) &&
-         ( iRecCodingType != CT_CELT ) )
+         ( iRecCodingType != CT_CELT ) &&
+         ( iRecCodingType != CT_OPUS ) )
     {
         return true;
     }
@@ -1373,6 +1385,20 @@ bool CProtocol::EvaluateReqNetwTranspPropsMes()
     return false; // no error
 }
 
+void CProtocol::CreateOpusSupportedMes()
+{
+    CreateAndSendMessage ( PROTMESSID_OPUS_SUPPORTED,
+                           CVector<uint8_t> ( 0 ) );
+}
+
+bool CProtocol::EvaluateOpusSupportedMes()
+{
+    // invoke message action
+    emit OpusSupported();
+
+    return false; // no error
+}
+
 
 // Connection less messages ----------------------------------------------------
 void CProtocol::CreateCLPingMes ( const CHostAddress& InetAddr, const int iMs )
diff --git a/src/protocol.h b/src/protocol.h
index 6fe7abd4..41e775d6 100755
--- a/src/protocol.h
+++ b/src/protocol.h
@@ -53,6 +53,7 @@
 #define PROTMESSID_REQ_CHANNEL_INFOS          23 // request channel infos for fader tag
 #define PROTMESSID_CONN_CLIENTS_LIST          24 // channel infos for connected clients
 #define PROTMESSID_CHANNEL_INFOS              25 // set channel infos
+#define PROTMESSID_OPUS_SUPPORTED             26 // tells that OPUS codec is supported
 
 // message IDs of connection less messages (CLM)
 // DEFINITION -> start at 1000, end at 1999, see IsConnectionLessMessageID
@@ -99,6 +100,7 @@ public:
     void CreatePingMes ( const int iMs );
     void CreateNetwTranspPropsMes ( const CNetworkTransportProps& NetTrProps );
     void CreateReqNetwTranspPropsMes();
+    void CreateOpusSupportedMes();
 
     void CreateCLPingMes ( const CHostAddress& InetAddr, const int iMs );
     void CreateCLPingWithNumClientsMes ( const CHostAddress& InetAddr,
@@ -212,6 +214,7 @@ protected:
     bool EvaluatePingMes               ( const CVector<uint8_t>& vecData );
     bool EvaluateNetwTranspPropsMes    ( const CVector<uint8_t>& vecData );
     bool EvaluateReqNetwTranspPropsMes();
+    bool EvaluateOpusSupportedMes();
 
     bool EvaluateCLPingMes               ( const CHostAddress&     InetAddr,
                                            const CVector<uint8_t>& vecData );
@@ -258,6 +261,7 @@ signals:
     void ChangeChanName ( QString strName );
     void ChangeChanInfo ( CChannelCoreInfo ChanInfo );
     void ReqChanInfo();
+    void OpusSupported();
     void ChatTextReceived ( QString strChatText );
     void PingReceived ( int iMs );
     void NetTranspPropsReceived ( CNetworkTransportProps NetworkTransportProps );