diff --git a/Conf.cpp b/Conf.cpp
index 06e3cb4..8629341 100644
--- a/Conf.cpp
+++ b/Conf.cpp
@@ -114,6 +114,7 @@ m_transparentEnabled(false),
 m_transparentRemoteAddress(),
 m_transparentRemotePort(0U),
 m_transparentLocalPort(0U),
+m_transparentSendFrameType(0U),
 m_umpEnabled(false),
 m_umpPort(),
 m_dstarEnabled(false),
@@ -464,6 +465,8 @@ bool CConf::read()
 			m_transparentRemotePort = (unsigned int)::atoi(value);
 		else if (::strcmp(key, "LocalPort") == 0)
 			m_transparentLocalPort = (unsigned int)::atoi(value);
+		else if (::strcmp(key, "SendFrameType") == 0)
+			m_transparentSendFrameType = (unsigned int)::atoi(value);
 	} else if (section == SECTION_UMP) {
 		if (::strcmp(key, "Enable") == 0)
 			m_umpEnabled = ::atoi(value) == 1;
@@ -1054,6 +1057,11 @@ unsigned int CConf::getTransparentLocalPort() const
 	return m_transparentLocalPort;
 }
 
+unsigned int CConf::getTransparentSendFrameType() const
+{
+	return m_transparentSendFrameType;
+}
+
 bool CConf::getUMPEnabled() const
 {
 	return m_umpEnabled;
diff --git a/Conf.h b/Conf.h
index 8243cd6..8b7d16c 100644
--- a/Conf.h
+++ b/Conf.h
@@ -99,6 +99,7 @@ public:
   std::string  getTransparentRemoteAddress() const;
   unsigned int getTransparentRemotePort() const;
   unsigned int getTransparentLocalPort() const;
+  unsigned int getTransparentSendFrameType() const;
 
   // The UMP section
   bool         getUMPEnabled() const;
@@ -322,6 +323,7 @@ private:
   std::string  m_transparentRemoteAddress;
   unsigned int m_transparentRemotePort;
   unsigned int m_transparentLocalPort;
+  unsigned int m_transparentSendFrameType;
 
   bool         m_umpEnabled;
   std::string  m_umpPort;
diff --git a/MMDVMHost.cpp b/MMDVMHost.cpp
index 054d113..54ff394 100644
--- a/MMDVMHost.cpp
+++ b/MMDVMHost.cpp
@@ -315,15 +315,18 @@ int CMMDVMHost::run()
 	unsigned int transparentPort = 0U;
 	CUDPSocket* transparentSocket = NULL;
 
+	unsigned int sendFrameType = 0U;
 	if (m_conf.getTransparentEnabled()) {
 		std::string remoteAddress = m_conf.getTransparentRemoteAddress();
 		unsigned int remotePort   = m_conf.getTransparentRemotePort();
 		unsigned int localPort    = m_conf.getTransparentLocalPort();
+		sendFrameType             = m_conf.getTransparentSendFrameType();
 
 		LogInfo("Transparent Data");
 		LogInfo("    Remote Address: %s", remoteAddress.c_str());
 		LogInfo("    Remote Port: %u", remotePort);
 		LogInfo("    Local Port: %u", localPort);
+		LogInfo("    Send Frame Type: %u", sendFrameType);
 
 		transparentAddress = CUDPSocket::lookup(remoteAddress);
 		transparentPort    = remotePort;
@@ -884,7 +887,7 @@ int CMMDVMHost::run()
 			unsigned int port = 0U;
 			len = transparentSocket->read(data, 200U, address, port);
 			if (len > 0U)
-				m_modem->writeTransparentData(data, len);
+				m_modem->writeTransparentData(data, len, sendFrameType);
 		}
 
 		unsigned int ms = stopWatch.elapsed();
diff --git a/Modem.cpp b/Modem.cpp
index 06bf916..e15ae7a 100644
--- a/Modem.cpp
+++ b/Modem.cpp
@@ -1085,7 +1085,7 @@ bool CModem::writePOCSAGData(const unsigned char* data, unsigned int length)
 	return true;
 }
 
-bool CModem::writeTransparentData(const unsigned char* data, unsigned int length)
+bool CModem::writeTransparentData(const unsigned char* data, unsigned int length, unsigned int sendFrameType)
 {
 	assert(data != NULL);
 	assert(length > 0U);
@@ -1096,7 +1096,19 @@ bool CModem::writeTransparentData(const unsigned char* data, unsigned int length
 	buffer[1U] = length + 3U;
 	buffer[2U] = MMDVM_TRANSPARENT;
 
-	::memcpy(buffer + 3U, data, length);
+	if (sendFrameType>0) {
+		::memcpy(buffer + 2U, data, length);
+		length--;
+		buffer[1U]--;
+		//when sendFrameType==1 , only 0x80 and 0x90 (MMDVM_SERIAL and MMDVM_TRANSPARENT) are allowed
+		//  and reverted to default (MMDVM_TRANSPARENT) for any other value
+		//when >1, frame type is not checked
+		if (sendFrameType==1) {
+			if ((buffer[2U] & 0xE0) != 0x80) buffer[2U] = MMDVM_TRANSPARENT;
+		}
+	} else {
+		::memcpy(buffer + 3U, data, length);
+	}
 
 	unsigned char len = length + 3U;
 	m_txTransparentData.addData(&len, 1U);
diff --git a/Modem.h b/Modem.h
index 52d2780..ef9c415 100644
--- a/Modem.h
+++ b/Modem.h
@@ -77,7 +77,7 @@ public:
 	bool writeP25Data(const unsigned char* data, unsigned int length);
 	bool writeNXDNData(const unsigned char* data, unsigned int length);
 	bool writePOCSAGData(const unsigned char* data, unsigned int length);
-	bool writeTransparentData(const unsigned char* data, unsigned int length);
+	bool writeTransparentData(const unsigned char* data, unsigned int length, unsigned int sendFrameType);
 
 	bool writeDMRStart(bool tx);
 	bool writeDMRShortLC(const unsigned char* lc);