diff --git a/SerialPort.cpp b/SerialPort.cpp
index 5fac49a..75c7309 100644
--- a/SerialPort.cpp
+++ b/SerialPort.cpp
@@ -357,11 +357,6 @@ void SerialPort::process()
                     }
                     break;
 
-                /** DFSI */
-                case CMD_DFSI_DATA:
-                    sendNAK(RSN_INVALID_REQUEST);
-                    break;
-
                 default:
                     // Handle this, send a NAK back
                     sendNAK(RSN_NAK);
diff --git a/SerialPort.h b/SerialPort.h
index 877b2b3..b788bee 100644
--- a/SerialPort.h
+++ b/SerialPort.h
@@ -92,8 +92,6 @@ enum DVM_COMMANDS {
     CMD_P25_LOST = 0x32U,
     CMD_P25_CLEAR = 0x33U,
 
-    CMD_DFSI_DATA = 0x40U,
-
     CMD_ACK = 0x70U,
     CMD_NAK = 0x7FU,
 
diff --git a/p25/P25RX.cpp b/p25/P25RX.cpp
index 8927604..dbca379 100644
--- a/p25/P25RX.cpp
+++ b/p25/P25RX.cpp
@@ -216,7 +216,7 @@ void P25RX::processBit(bool bit)
         uint8_t frame[P25_HDU_FRAME_LENGTH_BYTES + 1U];
         ::memcpy(frame + 1U, m_buffer, m_endPtr / 8U);
 
-        frame[0U] = 0x01U;
+        frame[0U] = 0x01U; // has sync
         serial.writeP25Data(frame, (m_endPtr / 8U) + 1U);
         reset();
     }
@@ -275,7 +275,7 @@ void P25RX::processVoice(bool bit)
         uint8_t frame[P25_TDU_FRAME_LENGTH_BYTES + 1U];
         ::memcpy(frame + 1U, m_buffer, m_endPtr / 8U);
 
-        frame[0U] = 0x01U;
+        frame[0U] = 0x01U; // has sync
         serial.writeP25Data(frame, P25_TDU_FRAME_LENGTH_BYTES + 1U);
 
         io.setDecode(false);
@@ -303,7 +303,7 @@ void P25RX::processVoice(bool bit)
             uint8_t frame[P25_LDU_FRAME_LENGTH_BYTES + 3U];
             ::memcpy(frame + 1U, m_buffer, m_endPtr / 8U);
 
-            frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;
+            frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U; // set sync flag
 #if defined(SEND_RSSI_DATA)
             uint16_t rssi = io.readRSSI();
             frame[217U] = (rssi >> 8) & 0xFFU;
@@ -373,7 +373,7 @@ void P25RX::processData(bool bit)
             uint8_t frame[P25_LDU_FRAME_LENGTH_BYTES + 1U];
             ::memcpy(frame + 1U, m_buffer, m_endPtr / 8U);
 
-            frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;
+            frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U; // set sync flag
             serial.writeP25Data(frame, P25_LDU_FRAME_LENGTH_BYTES + 1U);
         }
     }