diff --git a/DMRSlot.cpp b/DMRSlot.cpp
index 2067570..4d0d8a1 100644
--- a/DMRSlot.cpp
+++ b/DMRSlot.cpp
@@ -630,7 +630,7 @@ bool CDMRSlot::writeModem(unsigned char *data, unsigned int len)
 					if (!(m_rfTalkerId & TALKER_ID_HEADER)) {
 						if (m_rfTalkerId == TALKER_ID_NONE)
 							m_rfTalkerAlias.reset();
-						m_rfTalkerAlias.add(data, 6U);
+						m_rfTalkerAlias.add(0, data, 6U);
 						m_display->writeDMRTA(m_slotNo, (unsigned char*)m_rfTalkerAlias.get(), "R");
 
 						if (m_dumpTAData) {
@@ -649,7 +649,7 @@ bool CDMRSlot::writeModem(unsigned char *data, unsigned int len)
 					if (!(m_rfTalkerId & TALKER_ID_BLOCK1)) {
 						if (m_rfTalkerId == TALKER_ID_NONE)
 							m_rfTalkerAlias.reset();
-						m_rfTalkerAlias.add(data, 7U);
+						m_rfTalkerAlias.add(1, data, 7U);
 						m_display->writeDMRTA(m_slotNo, (unsigned char*)m_rfTalkerAlias.get(), "R");
 
 						if (m_dumpTAData) {
@@ -668,7 +668,7 @@ bool CDMRSlot::writeModem(unsigned char *data, unsigned int len)
 					if (!(m_rfTalkerId & TALKER_ID_BLOCK2)) {
 						if (m_rfTalkerId == TALKER_ID_NONE)
 							m_rfTalkerAlias.reset();
-						m_rfTalkerAlias.add(data, 7U);
+						m_rfTalkerAlias.add(2, data, 7U);
 						m_display->writeDMRTA(m_slotNo, (unsigned char*)m_rfTalkerAlias.get(), "R");
 
 						if (m_dumpTAData) {
@@ -687,7 +687,7 @@ bool CDMRSlot::writeModem(unsigned char *data, unsigned int len)
 					if (!(m_rfTalkerId & TALKER_ID_BLOCK3)) {
 						if (m_rfTalkerId == TALKER_ID_NONE)
 							m_rfTalkerAlias.reset();
-						m_rfTalkerAlias.add(data, 7U);
+						m_rfTalkerAlias.add(3, data, 7U);
 						m_display->writeDMRTA(m_slotNo, (unsigned char*)m_rfTalkerAlias.get(), "R");
 
 						if (m_dumpTAData) {
@@ -1424,7 +1424,7 @@ void CDMRSlot::writeNetwork(const CDMRData& dmrData)
 				if (!(m_netTalkerId & TALKER_ID_HEADER)) {
 					if (!m_netTalkerId)
 						m_rfTalkerAlias.reset();
-					m_rfTalkerAlias.add(data + 2U, 7U);
+					m_rfTalkerAlias.add(0, data + 2U, 7U);
 					m_display->writeDMRTA(m_slotNo, (unsigned char*)m_rfTalkerAlias.get(), "N");
 
 					if (m_dumpTAData) {
@@ -1439,7 +1439,7 @@ void CDMRSlot::writeNetwork(const CDMRData& dmrData)
 				if (!(m_netTalkerId & TALKER_ID_BLOCK1)) {
 					if (!m_netTalkerId)
 						m_rfTalkerAlias.reset();
-					m_rfTalkerAlias.add(data + 2U, 7U);
+					m_rfTalkerAlias.add(1, data + 2U, 7U);
 					m_display->writeDMRTA(m_slotNo, (unsigned char*)m_rfTalkerAlias.get(), "N");
 
 					if (m_dumpTAData) {
@@ -1454,7 +1454,7 @@ void CDMRSlot::writeNetwork(const CDMRData& dmrData)
 				if (!(m_netTalkerId & TALKER_ID_BLOCK2)) {
 					if (!m_netTalkerId)
 						m_rfTalkerAlias.reset();
-					m_rfTalkerAlias.add(data + 2U, 7U);
+					m_rfTalkerAlias.add(2, data + 2U, 7U);
 					m_display->writeDMRTA(m_slotNo, (unsigned char*)m_rfTalkerAlias.get(), "N");
 
 					if (m_dumpTAData) {
@@ -1469,7 +1469,7 @@ void CDMRSlot::writeNetwork(const CDMRData& dmrData)
 				if (!(m_netTalkerId & TALKER_ID_BLOCK3)) {
 					if (!m_netTalkerId)
 						m_rfTalkerAlias.reset();
-					m_rfTalkerAlias.add(data+2U, 7U);
+					m_rfTalkerAlias.add(3, data+2U, 7U);
 					m_display->writeDMRTA(m_slotNo, (unsigned char*)m_rfTalkerAlias.get(), "N");
 
 					if (m_dumpTAData) {
diff --git a/DMRTA.cpp b/DMRTA.cpp
index 8790842..27e6955 100644
--- a/DMRTA.cpp
+++ b/DMRTA.cpp
@@ -20,8 +20,7 @@
 
 CDMRTA::CDMRTA() :
 m_TA(),
-m_buf(),
-m_bufOffset(0)
+m_buf()
 {
 }
 
@@ -29,18 +28,37 @@ CDMRTA::~CDMRTA()
 {
 }
 
-bool CDMRTA::add(const unsigned char* data, unsigned int len)
+bool CDMRTA::add(unsigned int blockId, const unsigned char* data, unsigned int len)
 {
     assert(data != NULL);
 
-    if (m_bufOffset + len >= sizeof(m_buf)) {
+    unsigned int offset;
+    switch(blockId) {
+        case 0:
+            offset = 0;
+            break;
+        case 1:
+            offset = 6;
+            break;
+        case 2:
+            offset = 13;
+            break;
+        case 3:
+            offset = 20;
+            break;
+        default:
+            // invalid block id
+            reset();
+            return false;
+    }
+
+    if (offset + len >= sizeof(m_buf)) {
         // buffer overflow
         reset();
         return false;
     }
 
-    ::memcpy(m_buf + m_bufOffset, data, len);
-    m_bufOffset += len;
+    ::memcpy(m_buf + offset, data, len);
 
     decodeTA();
     return true;
@@ -55,7 +73,6 @@ void CDMRTA::reset()
 {
     ::memset(m_TA, 0, sizeof(m_TA));
     ::memset(m_buf, 0, sizeof(m_buf));
-    m_bufOffset = 0;
 }
 
 void CDMRTA::decodeTA()
diff --git a/DMRTA.h b/DMRTA.h
index 696f46e..d5fb483 100644
--- a/DMRTA.h
+++ b/DMRTA.h
@@ -20,7 +20,7 @@ public:
     CDMRTA();
     ~CDMRTA();
 
-    bool add(const unsigned char* data, unsigned int len);
+    bool add(unsigned int blockId, const unsigned char* data, unsigned int len);
     const unsigned char* get();
     void reset();
 
@@ -30,7 +30,6 @@ protected:
 private:
     char            m_TA[32];
     unsigned char   m_buf[32];
-    unsigned int    m_bufOffset;
 };
 
 #endif