diff --git a/LICENSE b/LICENSE
deleted file mode 100644
index 8da3c3d..0000000
--- a/LICENSE
+++ /dev/null
@@ -1,21 +0,0 @@
-MIT License
-
-Copyright (c) 2019 sh123
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
diff --git a/README.md b/README.md
index 57cfc17..4bffe5c 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ Can be used in two modes:
 - Arduino Timer library: https://github.com/contrem/arduino-timer
 
 # Software Setup
-- when setting up APRSDroid, use **"TNC (plaintext TNC2)"** connection protocol in Connection Preferences -> Connection Protocol
+- when setting up APRSDroid, use **"TNC (KISS)"** connection protocol in Connection Preferences -> Connection Protocol
 - go to esp32_loraprs.ino and make next changes based on your requirements
   - comment out / remove **LORAPRS_CLIENT** define if you are planning to run server mode for APRS-IS iGate
   - for server mode fill **LORAPRS_WIFI_SSID** and **LORAPRS_WIFI_KEY** with your WiFI AP data
diff --git a/esp32_loraprs.ino b/esp32_loraprs.ino
index 423d8c9..10b0b37 100644
--- a/esp32_loraprs.ino
+++ b/esp32_loraprs.ino
@@ -7,7 +7,11 @@
 
 #define LORAPRS_CLIENT
 
+#ifdef LORAPRS_CLIENT
+#define LORAPRS_FREQ        432.499E6
+#else
 #define LORAPRS_FREQ        432.5E6
+#endif
 
 #ifdef LORAPRS_CLIENT
 #define LORAPRS_BT_NAME     "loraprs_client"
diff --git a/loraprs.cpp b/loraprs.cpp
index 6adb054..27ecc64 100644
--- a/loraprs.cpp
+++ b/loraprs.cpp
@@ -1,12 +1,14 @@
 #include "loraprs.h"
 
-LoraPrs::LoraPrs(int loraFreq, String btName, String wifiName, 
-  String wifiKey, String aprsLoginCallsign, String aprsPass) 
+LoraPrs::LoraPrs(int loraFreq, const String & btName, const String & wifiName, 
+  const String & wifiKey, const String & aprsLoginCallsign, const String & aprsPass) 
   : serialBt_()
   , loraFreq_(loraFreq)
   , btName_(btName)
   , wifiName_(wifiName)
   , wifiKey_(wifiKey)
+  , kissState_(KissState::Void)
+  , kissCmd_(KissCmd::NoCmd)
 { 
     aprsLogin_ = "";
     aprsLogin_ += "user ";
@@ -25,7 +27,7 @@ void LoraPrs::setup()
   setupBt(btName_);
 }
 
-void LoraPrs::setupWifi(String wifiName, String wifiKey) 
+void LoraPrs::setupWifi(const String & wifiName, const String & wifiKey) 
 {
   if (wifiName.length() != 0) {    
     Serial.print("WIFI connecting to " + wifiName);
@@ -71,11 +73,12 @@ void LoraPrs::setupLora(int loraFreq)
   LoRa.setSignalBandwidth(CfgBw);
   LoRa.setCodingRate4(CfgCodingRate);
   LoRa.setTxPower(CfgPower);
+  LoRa.enableCrc();
   
   Serial.println("ok");  
 }
 
-void LoraPrs::setupBt(String btName) 
+void LoraPrs::setupBt(const String & btName)
 {
   if (btName.length() != 0) {
     Serial.print("BT init " + btName + "...");
@@ -98,16 +101,14 @@ void LoraPrs::loop()
   if (serialBt_.available()) {
     onBtReceived();
   }
-  if (LoRa.parsePacket()) {
-    onLoraReceived();
+  if (int packetSize = LoRa.parsePacket()) {
+    onLoraReceived(packetSize);
   }
   delay(10);
 }
 
-void LoraPrs::onAprsReceived(String aprsMessage)
+void LoraPrs::onAprsReceived(const String & aprsMessage)
 {
-  Serial.print(aprsMessage);
-
   if (WiFi.status() == WL_CONNECTED) {
     WiFiClient wifiClient;
 
@@ -116,35 +117,196 @@ void LoraPrs::onAprsReceived(String aprsMessage)
       return;
     }
     wifiClient.print(aprsLogin_);
+    Serial.print(aprsMessage);
     wifiClient.print(aprsMessage);
     wifiClient.stop();
+  } 
+  else {
+    Serial.println("Wifi not connected, not sent");
   }
 }
 
-void LoraPrs::onLoraReceived()
+String LoraPrs::decodeCall(byte *rxPtr) 
 {
-  String buf;
+  byte callsign[7];
+  char ssid;
+  
+  byte *ptr = rxPtr;
+
+  memset(callsign, 0, sizeof(callsign));
+    
+  for (int i = 0; i < 6; i++) {
+    char c = *(ptr++) >> 1;
+    callsign[i] = (c == ' ') ? '\0' : c;
+  }
+  callsign[6] = '\0';
+  ssid = (*ptr >> 1);
+  
+  String result = String((char*)callsign);
+  if (ssid >= '0' && ssid <= '9') {
+    result += String("-") + String(ssid);
+  }
+  return result;
+}
+
+String LoraPrs::convertAX25ToAprs(byte *rxPayload, int payloadLength, const String & signalReport)
+{
+  byte *rxPtr = rxPayload;
+  String srcCall, dstCall, rptFirst, rptSecond, result;
+
+  dstCall = decodeCall(rxPtr);
+  rxPtr += 7;
+
+  srcCall = decodeCall(rxPtr);
+  rxPtr += 7;
+  
+  if ((rxPayload[13] & 1) == 0) {
+    rptFirst = decodeCall(rxPtr);
+    rxPtr += 7;
+
+    if ((rxPayload[20] & 1) == 0) {
+      rptSecond = decodeCall(rxPtr);
+      rxPtr += 7;
+    }
+  }
+  
+  if (*(rxPtr++) != AX25Ctrl::UI) return result;
+  if (*(rxPtr++) != AX25Pid::NoLayer3) return result;
+  
+  result += srcCall + String(">") + dstCall;
+    
+  if (rptFirst.length() > 0) {
+    result += String(",") + rptFirst;
+  }
+  if (rptSecond.length() > 0) {
+    result += String(",") + rptSecond;
+  }
+
+  result += ":";
+
+  bool appendReport = ((char)*rxPtr == '=');
+  
+  while (rxPtr < rxPayload + payloadLength) {
+    result += String((char)*(rxPtr++));
+  }
+
+  if (appendReport) {
+    result += signalReport;
+  }
+  else {
+    result += "\n";
+  }
+  
+  return result;
+}
+
+void LoraPrs::onLoraReceived(int packetSize)
+{
+  int rxBufIndex = 0;
+  byte rxBuf[packetSize];
+
+  serialBt_.write(KissMarker::Fend);
+  serialBt_.write(KissCmd::Data);
+
   while (LoRa.available()) {
-    char c = (char)LoRa.read();
-    if (c != '\n')
-      buf += c;
+    byte rxByte = LoRa.read();
+
+    if (rxByte == KissMarker::Fend) {
+      serialBt_.write(KissMarker::Fesc);
+      serialBt_.write(KissMarker::Tfend);
+    }
+    else if (rxByte == KissMarker::Fesc) {
+      serialBt_.write(KissMarker::Fesc);
+      serialBt_.write(KissMarker::Tfesc);
+    }
+    else {
+      rxBuf[rxBufIndex++] = rxByte;
+      serialBt_.write(rxByte);
+    }
   }
-  for (int i; i < buf.length(); i++) {
-    serialBt_.write((uint8_t)buf[i]);
+
+  serialBt_.write(KissMarker::Fend);
+
+  String signalReport = String(" ") +  
+    String("RSSI: ") + 
+    String(LoRa.packetRssi()) + 
+    String(", ") +
+    String("SNR: ") + 
+    String(LoRa.packetSnr()) + 
+    String("dB, ") +
+    String("ERR: ") + 
+    String(LoRa.packetFrequencyError()) + 
+    String("Hz\n");
+
+  String aprsMsg = convertAX25ToAprs(rxBuf, rxBufIndex, signalReport);
+
+  if (aprsMsg.length() != 0) {
+    onAprsReceived(aprsMsg);
   }
-  onAprsReceived(buf + " " +
-    "RSSI: " + String(LoRa.packetRssi()) + ", " +
-    "SNR: " + String(LoRa.packetSnr()) + "dB, " +
-    "ERR: " + String(LoRa.packetFrequencyError()) + "Hz\n");
+
   delay(50);
 }
 
-void LoraPrs::onBtReceived() 
+void LoraPrs::kissResetState()
 {
-  LoRa.beginPacket();
-  while (serialBt_.available()) {
-    char c = (char)serialBt_.read();
-    LoRa.print(c);
-  }
-  LoRa.endPacket();
+  kissCmd_ = KissCmd::NoCmd;
+  kissState_ = KissState::Void;
+}
+
+void LoraPrs::onBtReceived() 
+{ 
+  while (serialBt_.available()) {
+    byte txByte = serialBt_.read();
+
+    switch (kissState_) {
+      case KissState::Void:
+        if (txByte == KissMarker::Fend) {
+          kissCmd_ = KissCmd::NoCmd;
+          kissState_ = KissState::GetCmd;
+        }
+        break;
+      case KissState::GetCmd:
+        if (txByte != KissMarker::Fend) {
+          if (txByte == KissCmd::Data) {
+            LoRa.beginPacket();
+            kissCmd_ = (KissCmd)txByte;
+            kissState_ = KissState::GetData;
+          }
+          else {
+            kissResetState();
+          }
+        }
+        break;
+      case KissState::GetData:
+        if (txByte == KissMarker::Fesc) {
+          kissState_ = KissState::Escape;
+        }
+        else if (txByte == KissMarker::Fend) {
+          if (kissCmd_ == KissCmd::Data) {
+            LoRa.endPacket();
+          }
+          kissResetState();
+        }
+        else {
+          LoRa.write(txByte);
+        }
+        break;
+      case KissState::Escape:
+        if (txByte == KissMarker::Tfend) {
+          LoRa.write(KissMarker::Fend);
+          kissState_ = KissState::GetData;
+        }
+        else if (txByte == KissMarker::Tfesc) {
+          LoRa.write(KissMarker::Fesc);
+          kissState_ = KissState::GetData;
+        }
+        else {
+          kissResetState();
+        }
+        break;
+      default:
+        break;
+    }
+  }
+  delay(20);
 }
diff --git a/loraprs.h b/loraprs.h
index a0e32e7..101c8d1 100644
--- a/loraprs.h
+++ b/loraprs.h
@@ -11,6 +11,60 @@
 class LoraPrs
 {
 public:
+  LoraPrs(int loraFreq, const String & btName, const String & wifiName, 
+    const String & wifiKey, const String & aprsLoginCallsign, const String & aprsPass);
+  
+  void setup();
+  void loop();
+
+private:
+  void setupWifi(const String & wifiName, const String & wifiKey);
+  void setupLora(int loraFreq);
+  void setupBt(const String & btName);
+
+  void reconnectWifi();
+  
+  void onLoraReceived(int packetSize);
+  void onBtReceived();
+
+  void kissResetState();
+
+  void onAprsReceived(const String & aprsMessage);
+
+  bool isAX25CrcValid(byte *rxPayload, int payloadLength);
+  String convertAX25ToAprs(byte *rxPayload, int payloadLength, const String & signalReport);
+  String decodeCall(byte *rxPtr);
+
+  uint16_t updateCrcCcit(uint8_t newByte, uint16_t prevCrc);
+  
+private:
+  enum KissMarker {
+    Fend = 0xc0,
+    Fesc = 0xdb,
+    Tfend = 0xdc,
+    Tfesc = 0xdd
+  };
+
+  enum KissState {
+    Void = 0,
+    GetCmd,
+    GetData,
+    Escape
+  };
+
+  enum KissCmd {
+    Data = 0x00,
+    NoCmd = 0x80
+  };
+
+  enum AX25Ctrl {
+    UI = 0x03
+  };
+
+  enum AX25Pid {
+    NoLayer3 = 0xf0
+  };
+  
   const String CfgLoraprsVersion = "LoRAPRS 0.1";
   
   const byte CfgPinSs = 5;
@@ -26,32 +80,17 @@ public:
   const int CfgAprsPort = 14580;
   const String CfgAprsHost = "rotate.aprs2.net";
 
-public:
-  LoraPrs(int loraFreq, String btName, String wifiName, 
-    String wifiKey, String aprsLoginCallsign, String aprsPass);
-  
-  void setup();
-  void loop();
-
 private:
-  void setupWifi(String wifiName, String wifiKey);
-  void setupLora(int loraFreq);
-  void setupBt(String btName);
-
-  void reconnectWifi();
-  
-  void onLoraReceived();
-  void onBtReceived();
-  void onAprsReceived(String aprsMessage);
-  
-private:
-  BluetoothSerial serialBt_;
-  
   int loraFreq_;
   String btName_;
   String wifiName_;
   String wifiKey_;
   String aprsLogin_;
+
+  KissCmd kissCmd_;
+  KissState kissState_;
+
+  BluetoothSerial serialBt_;
 };
 
 #endif // LORAPRS_H