diff --git a/NXDNControl.cpp b/NXDNControl.cpp
index 4eeea24..4023dc6 100644
--- a/NXDNControl.cpp
+++ b/NXDNControl.cpp
@@ -230,7 +230,7 @@ bool CNXDNControl::processVoice(unsigned char usc, unsigned char option, unsigne
 
 		scrambler(data + 2U);
 
-		// writeNetwork(data, m_rfFrames, );
+		writeNetwork(data, false);
 
 #if defined(DUMP_NXDN)
 		writeFile(data + 2U);
@@ -401,7 +401,7 @@ bool CNXDNControl::processVoice(unsigned char usc, unsigned char option, unsigne
 
 			scrambler(start + 2U);
 
-			// writeNetwork(start, m_rfFrames, );
+			writeNetwork(start, false);
 
 #if defined(DUMP_NXDN)
 			writeFile(start + 2U);
@@ -515,7 +515,7 @@ bool CNXDNControl::processVoice(unsigned char usc, unsigned char option, unsigne
 
 		scrambler(data + 2U);
 
-		// writeNetwork(data, m_rfFrames, );
+		writeNetwork(data, false);
 
 #if defined(DUMP_NXDN)
 		writeFile(data + 2U);
@@ -575,6 +575,9 @@ bool CNXDNControl::processData(unsigned char option, unsigned char *data)
 
 		LogMessage("NXDN, received RF data header from %s to %s%u, %u blocks", source.c_str(), grp ? "TG " : "", dstId, frames);
 
+		m_rfLayer3 = layer3;
+		m_rfFrames = 0U;
+
 		m_rfState = RS_RF_DATA;
 
 #if defined(DUMP_NXDN)
@@ -607,21 +610,20 @@ bool CNXDNControl::processData(unsigned char option, unsigned char *data)
 
 	scrambler(data + 2U);
 
-	writeQueueNet(data);
+	writeNetwork(data, true);
 
 	if (m_duplex)
 		writeQueueRF(data);
 
+	m_rfFrames++;
+
 #if defined(DUMP_NXDN)
 	writeFile(data + 2U);
 #endif
 
-	if (validUDCH) {
-		unsigned char type = layer3.getMessageType();
-		if (type == NXDN_MESSAGE_TYPE_TX_REL) {
-			LogMessage("NXDN, ended RF data transmission");
-			writeEndRF();
-		}
+	if (data[0U] == TAG_EOT) {
+		LogMessage("NXDN, ended RF data transmission");
+		writeEndRF();
 	}
 
 	return true;
@@ -753,7 +755,7 @@ void CNXDNControl::writeQueueNet(const unsigned char *data)
 	m_queue.addData(data, len);
 }
 
-void CNXDNControl::writeNetwork(const unsigned char *data, unsigned int count, bool end)
+void CNXDNControl::writeNetwork(const unsigned char *data, bool dat)
 {
 	assert(data != NULL);
 
@@ -767,7 +769,9 @@ void CNXDNControl::writeNetwork(const unsigned char *data, unsigned int count, b
 	unsigned short dstId = m_rfLayer3.getDestinationGroupId();
 	bool grp             = m_rfLayer3.getIsGroup();
 
-	m_network->write(data + 2U, srcId, grp, dstId, count % 256U, end);
+	bool end = data[0U] == TAG_EOT;
+
+	m_network->write(data + 2U, srcId, grp, dstId, dat, m_rfFrames, end);
 }
 
 void CNXDNControl::scrambler(unsigned char* data) const
diff --git a/NXDNControl.h b/NXDNControl.h
index 5f000e7..d0934b6 100644
--- a/NXDNControl.h
+++ b/NXDNControl.h
@@ -86,7 +86,7 @@ private:
 
 	void writeQueueRF(const unsigned char* data);
 	void writeQueueNet(const unsigned char* data);
-	void writeNetwork(const unsigned char* data, unsigned int count, bool end);
+	void writeNetwork(const unsigned char* data, bool dat);
 	void writeNetwork();
 
 	void scrambler(unsigned char* data) const;
diff --git a/NXDNNetwork.cpp b/NXDNNetwork.cpp
index 6453829..53cfb05 100644
--- a/NXDNNetwork.cpp
+++ b/NXDNNetwork.cpp
@@ -32,11 +32,14 @@ CNXDNNetwork::CNXDNNetwork(const std::string& myAddress, unsigned int myPort, co
 m_socket(myAddress, myPort),
 m_address(),
 m_port(gatewayPort),
+m_callsign(callsign),
 m_debug(debug),
 m_enabled(false),
 m_buffer(1000U, "NXDN Network"),
 m_pollTimer(1000U, 5U)
 {
+	m_callsign.resize(10U, ' ');
+
 	m_address = CUDPSocket::lookup(gatewayAddress);
 }
 
@@ -56,7 +59,7 @@ bool CNXDNNetwork::open()
 	return m_socket.open();
 }
 
-bool CNXDNNetwork::write(const unsigned char* data, unsigned short src, bool grp, unsigned short dst, unsigned char cnt, bool end)
+bool CNXDNNetwork::write(const unsigned char* data, unsigned short src, bool grp, unsigned short dst, bool dat, unsigned char cnt, bool end)
 {
 	assert(data != NULL);
 
@@ -72,7 +75,8 @@ bool CNXDNNetwork::write(const unsigned char* data, unsigned short src, bool grp
 	buffer[6U] = (src >> 8) & 0xFFU;
 
 	buffer[7U]  = grp ? 0x01U : 0x00U;
-	buffer[7U] |= end ? 0x80U : 0x00U;
+	buffer[7U] |= dat ? 0x02U : 0x00U;
+	buffer[7U] |= end ? 0x04U : 0x00U;
 
 	buffer[8U] = (dst >> 8) & 0xFFU;
 	buffer[9U] = (dst >> 8) & 0xFFU;
@@ -97,10 +101,13 @@ bool CNXDNNetwork::writePoll()
 	buffer[3U] = 'N';
 	buffer[4U] = 'P';
 
-	if (m_debug)
-		CUtils::dump(1U, "NXDN Network Poll Sent", buffer, 5U);
+	for (unsigned int i = 0U; i < 10U; i++)
+		buffer[5U + i] = m_callsign.at(i);
 
-	return m_socket.write(buffer, 5U, m_address, m_port);
+	if (m_debug)
+		CUtils::dump(1U, "NXDN Network Poll Sent", buffer, 15U);
+
+	return m_socket.write(buffer, 15U, m_address, m_port);
 }
 
 void CNXDNNetwork::clock(unsigned int ms)
@@ -142,7 +149,7 @@ void CNXDNNetwork::clock(unsigned int ms)
 	m_buffer.addData(buffer, 59U);
 }
 
-unsigned int CNXDNNetwork::read(unsigned char* data, unsigned short& src, bool& grp, unsigned short& dst, unsigned char& cnt, bool& end)
+unsigned int CNXDNNetwork::read(unsigned char* data, unsigned short& src, bool& grp, unsigned short& dst, bool& dat, unsigned char& cnt, bool& end)
 {
 	assert(data != NULL);
 
@@ -154,7 +161,8 @@ unsigned int CNXDNNetwork::read(unsigned char* data, unsigned short& src, bool&
 
 	src = (buffer[5U] << 8) + buffer[6U];
 	grp = (buffer[7U] & 0x01U) == 0x01U;
-	end = (buffer[7U] & 0x80U) == 0x80U;
+	dat = (buffer[7U] & 0x02U) == 0x02U;
+	end = (buffer[7U] & 0x04U) == 0x04U;
 	dst = (buffer[8U] << 8) + buffer[9U];
 
 	cnt = buffer[10U];
diff --git a/NXDNNetwork.h b/NXDNNetwork.h
index c69602a..3ef9fda 100644
--- a/NXDNNetwork.h
+++ b/NXDNNetwork.h
@@ -36,9 +36,9 @@ public:
 
 	void enable(bool enabled);
 
-	bool write(const unsigned char* data, unsigned short src, bool grp, unsigned short dst, unsigned char cnt, bool end);
+	bool write(const unsigned char* data, unsigned short src, bool grp, unsigned short dst, bool dat, unsigned char cnt, bool end);
 
-	unsigned int read(unsigned char* data, unsigned short& src, bool& grp, unsigned short& dst, unsigned char& cnt, bool& end);
+	unsigned int read(unsigned char* data, unsigned short& src, bool& grp, unsigned short& dst, bool& dat, unsigned char& cnt, bool& end);
 
 	void reset();
 
@@ -50,6 +50,7 @@ private:
 	CUDPSocket     m_socket;
 	in_addr        m_address;
 	unsigned int   m_port;
+	std::string    m_callsign;
 	bool           m_debug;
 	bool           m_enabled;
 	CRingBuffer<unsigned char> m_buffer;