diff --git a/NXDNControl.cpp b/NXDNControl.cpp
index 55ec3a6..edfedcb 100644
--- a/NXDNControl.cpp
+++ b/NXDNControl.cpp
@@ -245,7 +245,7 @@ bool CNXDNControl::processVoice(unsigned char usc, unsigned char option, unsigne
 
 		scrambler(data + 2U);
 
-		writeNetwork(netData, true);
+		writeNetwork(netData, data[0U] == TAG_EOT ? NNMT_VOICE_TRAILER : NNMT_VOICE_HEADER);
 
 #if defined(DUMP_NXDN)
 		writeFile(data + 2U);
@@ -424,7 +424,7 @@ bool CNXDNControl::processVoice(unsigned char usc, unsigned char option, unsigne
 
 			scrambler(start + 2U);
 
-			writeNetwork(netData, true);
+			writeNetwork(netData, NNMT_VOICE_HEADER);
 
 #if defined(DUMP_NXDN)
 			writeFile(start + 2U);
@@ -529,7 +529,7 @@ bool CNXDNControl::processVoice(unsigned char usc, unsigned char option, unsigne
 
 		scrambler(data + 2U);
 
-		writeNetwork(netData, false);
+		writeNetwork(netData, NNMT_VOICE_BODY);
 
 #if defined(DUMP_NXDN)
 		writeFile(data + 2U);
@@ -618,8 +618,10 @@ bool CNXDNControl::processData(unsigned char option, unsigned char *data)
 
 	udch.getRaw(netData + 1U);
 
+	unsigned char type = NXDN_MESSAGE_TYPE_DCALL_DATA;
+
 	if (validUDCH) {
-		unsigned char type = layer3.getMessageType();
+		type = layer3.getMessageType();
 		data[0U] = type == NXDN_MESSAGE_TYPE_TX_REL ? TAG_EOT : TAG_DATA;
 
 		udch.setRAN(m_ran);
@@ -631,7 +633,17 @@ bool CNXDNControl::processData(unsigned char option, unsigned char *data)
 
 	scrambler(data + 2U);
 
-	writeNetwork(netData, true);
+	switch (type) {
+	case NXDN_MESSAGE_TYPE_DCALL_HDR:
+		writeNetwork(netData, NNMT_DATA_HEADER);
+		break;
+	case NXDN_MESSAGE_TYPE_TX_REL:
+		writeNetwork(netData, NNMT_DATA_TRAILER);
+		break;
+	default:
+		writeNetwork(netData, NNMT_DATA_BODY);
+		break;
+	}
 
 	if (m_duplex)
 		writeQueueRF(data);
@@ -1005,7 +1017,7 @@ void CNXDNControl::writeQueueNet(const unsigned char *data)
 	m_queue.addData(data, len);
 }
 
-void CNXDNControl::writeNetwork(const unsigned char *data, bool single)
+void CNXDNControl::writeNetwork(const unsigned char *data, NXDN_NETWORK_MESSAGE_TYPE type)
 {
 	assert(data != NULL);
 
@@ -1015,7 +1027,7 @@ void CNXDNControl::writeNetwork(const unsigned char *data, bool single)
 	if (m_rfTimeoutTimer.isRunning() && m_rfTimeoutTimer.hasExpired())
 		return;
 
-	m_network->write(data, single);
+	m_network->write(data, type);
 }
 
 void CNXDNControl::scrambler(unsigned char* data) const
diff --git a/NXDNControl.h b/NXDNControl.h
index 01651d6..0bb38d7 100644
--- a/NXDNControl.h
+++ b/NXDNControl.h
@@ -84,7 +84,7 @@ private:
 
 	void writeQueueRF(const unsigned char* data);
 	void writeQueueNet(const unsigned char* data);
-	void writeNetwork(const unsigned char* data, bool single);
+	void writeNetwork(const unsigned char* data, NXDN_NETWORK_MESSAGE_TYPE type);
 	void writeNetwork();
 
 	void scrambler(unsigned char* data) const;
diff --git a/NXDNNetwork.cpp b/NXDNNetwork.cpp
index 04703b0..f724dea 100644
--- a/NXDNNetwork.cpp
+++ b/NXDNNetwork.cpp
@@ -56,7 +56,7 @@ bool CNXDNNetwork::open()
 	return m_socket.open();
 }
 
-bool CNXDNNetwork::write(const unsigned char* data, bool single)
+bool CNXDNNetwork::write(const unsigned char* data, NXDN_NETWORK_MESSAGE_TYPE type)
 {
 	assert(data != NULL);
 
@@ -72,9 +72,28 @@ bool CNXDNNetwork::write(const unsigned char* data, bool single)
 	buffer[6U] = 0x08U;
 	buffer[7U] = 0xE0U;
 
-	buffer[37U] = 0x23U;
-	buffer[38U] = single ? 0x1CU : 0x10U;
-	buffer[39U] = 0x21U;
+	switch (type) {
+	case NNMT_VOICE_HEADER:
+	case NNMT_VOICE_TRAILER:
+		buffer[37U] = 0x23U;
+		buffer[38U] = 0x1CU;
+		buffer[39U] = 0x21U;
+		break;
+	case NNMT_VOICE_BODY:
+		buffer[37U] = 0x23U;
+		buffer[38U] = 0x10U;
+		buffer[39U] = 0x21U;
+		break;
+	case NNMT_DATA_HEADER:
+	case NNMT_DATA_BODY:
+	case NNMT_DATA_TRAILER:
+		buffer[37U] = 0x23U;
+		buffer[38U] = 0x02U;
+		buffer[39U] = 0x18U;
+		break;
+	default:
+		return false;
+	}
 
 	::memcpy(buffer + 40U, data, 33U);
 
diff --git a/NXDNNetwork.h b/NXDNNetwork.h
index 4a6c053..3a5b784 100644
--- a/NXDNNetwork.h
+++ b/NXDNNetwork.h
@@ -27,6 +27,15 @@
 #include <cstdint>
 #include <string>
 
+enum NXDN_NETWORK_MESSAGE_TYPE {
+	NNMT_VOICE_HEADER,
+	NNMT_VOICE_BODY,
+	NNMT_VOICE_TRAILER,
+	NNMT_DATA_HEADER,
+	NNMT_DATA_BODY,
+	NNMT_DATA_TRAILER
+};
+
 class CNXDNNetwork {
 public:
 	CNXDNNetwork(const std::string& localAddress, unsigned int localPort, const std::string& gatewayAddress, unsigned int gatewayPort, bool debug);
@@ -36,7 +45,7 @@ public:
 
 	void enable(bool enabled);
 
-	bool write(const unsigned char* data, bool single);
+	bool write(const unsigned char* data, NXDN_NETWORK_MESSAGE_TYPE type);
 
 	bool read(unsigned char* data);
 
diff --git a/NXDNUDCH.cpp b/NXDNUDCH.cpp
index 55c81bf..bdba864 100644
--- a/NXDNUDCH.cpp
+++ b/NXDNUDCH.cpp
@@ -187,8 +187,6 @@ void CNXDNUDCH::getRaw(unsigned char* data) const
 
 	::memset(data, 0x00U, 25U);
 	::memcpy(data, m_data, 23U);
-
-	CNXDNCRC::encodeCRC15(data, 184U);
 }
 
 void CNXDNUDCH::setRAN(unsigned char ran)