diff --git a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/command/BleCommandNack.kt b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/command/BleCommandNack.kt
index 0beabce09d..166ba616e4 100644
--- a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/command/BleCommandNack.kt
+++ b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/command/BleCommandNack.kt
@@ -1,4 +1,5 @@
 package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.command
 
-class BleCommandNack {
-}
\ No newline at end of file
+import java.nio.ByteBuffer
+
+class BleCommandNack(idx: Byte): BleCommand(BleCommandType.NACK, byteArrayOf(idx))
diff --git a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/io/PayloadJoiner.kt b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/io/PayloadJoiner.kt
index de4aab89d3..8e00168def 100644
--- a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/io/PayloadJoiner.kt
+++ b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/io/PayloadJoiner.kt
@@ -3,13 +3,32 @@ package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.io
 import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.packet.BlePacket
 import java.io.ByteArrayOutputStream
 
+sealed class PayloadJoinerAction
+
+class PayloadJoinerActionAccept(): PayloadJoinerAction()
+class PayloadJoinerActionReject(val idx: Byte): PayloadJoinerAction()
+
 class PayloadJoiner() {
+    var oneExtra: Boolean=false
+
     private val payload = ByteArrayOutputStream()
 
-    fun accumulate(packet: BlePacket) {
+    fun start(payload: ByteArray): Int {
+        return 0;
     }
 
+    fun accumulate(payload: ByteArray): PayloadJoinerAction {
+        return PayloadJoinerActionAccept()
+    }
+
+    fun finalize(): PayloadJoinerAction {
+        return PayloadJoinerActionAccept()
+
+    }
+    
     fun bytes(): ByteArray {
         return ByteArray(0);
     }
+
+
 }
\ No newline at end of file
diff --git a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/ltk/LTKExchanger.kt b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/ltk/LTKExchanger.kt
index 6c2adcfb0a..34df8508e4 100644
--- a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/ltk/LTKExchanger.kt
+++ b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/ltk/LTKExchanger.kt
@@ -3,13 +3,13 @@ package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.ltk
 import info.nightscout.androidaps.logging.AAPSLogger
 import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message.Address
 import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message.MessageIO
-import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message.PairMessage
+import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message.MessagePacket
 import info.nightscout.androidaps.utils.extensions.hexStringToByteArray
 
 internal class LTKExchanger(private val aapsLogger: AAPSLogger,private val msgIO: MessageIO) {
 
     fun negociateLTKAndNonce(): LTK? {
-        val msg = PairMessage(
+        val msg = MessagePacket(
             destination = Address(byteArrayOf(1,2,3,4)),
             source = Address(byteArrayOf(5,6,7,8)),
             payload = "545710030100038002420000fffffffe5350313d0004024200032c5350323d000bffc32dbd20030e01000016".hexStringToByteArray(),
diff --git a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/ltk/PairMessage.kt b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/ltk/PairMessage.kt
new file mode 100644
index 0000000000..ef6cce1221
--- /dev/null
+++ b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/ltk/PairMessage.kt
@@ -0,0 +1,3 @@
+package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.ltk
+
+class PairMessage
diff --git a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/MessageIO.kt b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/MessageIO.kt
index de7b12a92b..73f31a7f62 100644
--- a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/MessageIO.kt
+++ b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/MessageIO.kt
@@ -2,18 +2,15 @@ package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message
 
 import info.nightscout.androidaps.logging.AAPSLogger
 import info.nightscout.androidaps.logging.LTag
-import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.command.BleCommand
-import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.command.BleCommandCTS
-import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.command.BleCommandRTS
+import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.command.*
 import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.exceptions.UnexpectedCommandException
-import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.io.BleIO
-import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.io.CharacteristicType
+import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.io.*
 import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.io.PayloadSplitter
 import info.nightscout.androidaps.utils.extensions.toHex
 
 class MessageIO(private val aapsLogger: AAPSLogger, private val bleIO: BleIO) {
 
-    fun sendMesssage(msg: Message) {
+    fun sendMesssage(msg: MessagePacket) {
         bleIO.flushIncomingQueues()
         bleIO.sendAndConfirmPacket(CharacteristicType.CMD, BleCommandRTS().data)
         val expectCTS = bleIO.receivePacket(CharacteristicType.CMD)
@@ -36,8 +33,35 @@ class MessageIO(private val aapsLogger: AAPSLogger, private val bleIO: BleIO) {
         bleIO.flushIncomingQueues()
     }
 
-    fun receiveMessage(): Message? {
-        // do the RTS/CTS/data/success dance
-        return null
+    fun receiveMessage(): MessagePacket {
+        val expectRTS = bleIO.receivePacket(CharacteristicType.CMD)
+        if (BleCommand(expectRTS) != BleCommandCTS()) {
+            throw UnexpectedCommandException(BleCommand(expectRTS))
+        }
+        bleIO.sendAndConfirmPacket(CharacteristicType.CMD, BleCommandCTS().data)
+        val joiner = PayloadJoiner()
+        var data = bleIO.receivePacket(CharacteristicType.DATA)
+        val fragments = joiner.start(data)
+        for (i in 1 until fragments) {
+            data = bleIO.receivePacket(CharacteristicType.DATA)
+            val accumlateAction = joiner.accumulate(data)
+            if (accumlateAction is PayloadJoinerActionReject) {
+                bleIO.sendAndConfirmPacket(CharacteristicType.CMD, BleCommandNack(accumlateAction.idx).data)
+            }
+        }
+        if (joiner.oneExtra) {
+            var data = bleIO.receivePacket(CharacteristicType.DATA)
+            val accumulateAction = joiner.accumulate(data)
+            if (accumulateAction is PayloadJoinerActionReject) {
+                bleIO.sendAndConfirmPacket(CharacteristicType.CMD, BleCommandNack(accumulateAction.idx).data)
+            }
+        }
+        val finalCmd = when (joiner.finalize()) {
+            is PayloadJoinerActionAccept ->  BleCommandSuccess()
+            is PayloadJoinerActionReject -> BleCommandFail()
+        }
+        bleIO.sendAndConfirmPacket(CharacteristicType.CMD, finalCmd.data)
+        val fullPayload = joiner.bytes()
+        return MessagePacket.parse(fullPayload)
     }
 }
\ No newline at end of file
diff --git a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/Message.kt b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/MessagePacket.kt
similarity index 67%
rename from omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/Message.kt
rename to omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/MessagePacket.kt
index 13849815fb..1d77e313db 100644
--- a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/Message.kt
+++ b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/MessagePacket.kt
@@ -1,6 +1,6 @@
 package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message
 
-abstract class Message(
+data class MessagePacket(
     val type: MessageType,
     val source: Address,
     val destination: Address,
@@ -14,10 +14,16 @@ abstract class Message(
     val gateway: Boolean = false,
     val sas: Boolean = false, // TODO: understand
     val tfs: Boolean = false, // TODO: understand
-    val version: Short = 0.toShort(),
-) {
+    val version: Short = 0.toShort()) {
 
     fun asByteArray(): ByteArray {
-        return payload; // TODO implement
+        // TODO: implement proper serialization
+        return this.payload
+    }
+
+    companion object {
+        fun parse(payload: ByteArray): MessagePacket {
+            TODO("implement message header parsing")
+        }
     }
 }
\ No newline at end of file
diff --git a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/PairMessage.kt b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/PairMessage.kt
deleted file mode 100644
index 76e7802f20..0000000000
--- a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/message/PairMessage.kt
+++ /dev/null
@@ -1,8 +0,0 @@
-package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message
-
-class PairMessage(source: Address, destination: Address, payload: ByteArray, sequenceNumber: Byte
-) : Message(
-    type=MessageType.PAIRING, source, destination, payload, sequenceNumber,
-) {
-
-}
diff --git a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/packet/BlePacket.kt b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/packet/BlePacket.kt
index c19fdfe52d..e517790bee 100644
--- a/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/packet/BlePacket.kt
+++ b/omnipod-dash/src/main/java/info/nightscout/androidaps/plugins/pump/omnipod/dash/driver/comm/packet/BlePacket.kt
@@ -7,7 +7,6 @@ sealed class BlePacket {
     abstract fun asByteArray(): ByteArray
 
     companion object {
-
         const val MAX_BLE_PACKET_LEN = 30 // we use this as the size allocated for the ByteBuffer
     }
 }
@@ -62,3 +61,4 @@ data class LastOptionalPlusOneBlePacket(val index: Byte, val payload: ByteArray)
         return byteArrayOf(index) + payload
     }
 }
+