diff --git a/lib/ble/ble_winrt.cpp b/lib/ble/ble_winrt.cpp
index 8ab74725..a8659594 100644
--- a/lib/ble/ble_winrt.cpp
+++ b/lib/ble/ble_winrt.cpp
@@ -2,6 +2,7 @@
  * Каждая отправка адресована link/subscribedClient; одна незавершённая операция на link.
  * Слабые ссылки в WinRT handlers и отменяемый posted_task исключают обращения к уничтоженному core. */
 #include "ble_backend.h"
+#include "ble_identity.h"
 #include "../u_async.h"
 #include "../mem.h"
 #include "../debug_config.h"
diff --git a/tools/chatgui-android/app/src/main/java/com/utun/chat/data/BleRadio.kt b/tools/chatgui-android/app/src/main/java/com/utun/chat/data/BleRadio.kt
index 579cb655..9a98d7ad 100644
--- a/tools/chatgui-android/app/src/main/java/com/utun/chat/data/BleRadio.kt
+++ b/tools/chatgui-android/app/src/main/java/com/utun/chat/data/BleRadio.kt
@@ -176,8 +176,8 @@ object BleRadio {
                 }
                 override fun onDescriptorWriteRequest(device: BluetoothDevice, requestId: Int, descriptor: BluetoothGattDescriptor,
                     preparedWrite: Boolean, responseNeeded: Boolean, offset: Int, value: ByteArray) = post {
-                    val expected = if (descriptor.characteristic.uuid == txUuid) BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
-                        else BluetoothGattDescriptor.ENABLE_INDICATION_VALUE
+                    val expected = if (descriptor.characteristic.uuid == inviteUuid) BluetoothGattDescriptor.ENABLE_INDICATION_VALUE
+                        else BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
                     val valid = incoming && descriptor.uuid == cccUuid && descriptor.characteristic.uuid in listOf(txUuid, inviteUuid, ackUuid) &&
                         !preparedWrite && offset == 0 && value.contentEquals(expected)
                     var link = links.values.find { !it.outgoing && it.device.address == device.address }
@@ -207,7 +207,7 @@ object BleRadio {
                     preparedWrite: Boolean, responseNeeded: Boolean, offset: Int, value: ByteArray) = post {
                     val link = links.values.find { !it.outgoing && it.device.address == device.address }
                     val valid = link != null && link.opened && characteristic.uuid in listOf(rxUuid, inviteUuid, ackUuid) &&
-                        !preparedWrite && responseNeeded == (characteristic.uuid != rxUuid) && offset == 0
+                        !preparedWrite && responseNeeded == (characteristic.uuid == inviteUuid) && offset == 0
                     if (valid) emit(3, link!!.token, arg = wireChannel(characteristic.uuid), data = value.copyOf())
                     if (responseNeeded) respond(device, requestId, if (valid) 0 else BluetoothGatt.GATT_REQUEST_NOT_SUPPORTED)
                     if (!valid) log("WARN", "Write rejected address=${device.address} characteristic=${characteristic.uuid} " +
@@ -253,7 +253,7 @@ object BleRadio {
             }
             service.addCharacteristic(invite)
             ack = BluetoothGattCharacteristic(ackUuid,
-                BluetoothGattCharacteristic.PROPERTY_WRITE or BluetoothGattCharacteristic.PROPERTY_INDICATE,
+                BluetoothGattCharacteristic.PROPERTY_WRITE_NO_RESPONSE or BluetoothGattCharacteristic.PROPERTY_NOTIFY,
                 BluetoothGattCharacteristic.PERMISSION_WRITE).apply {
                 addDescriptor(BluetoothGattDescriptor(cccUuid, BluetoothGattDescriptor.PERMISSION_WRITE))
             }
@@ -405,8 +405,10 @@ object BleRadio {
                 if (characteristic.properties and BluetoothGattCharacteristic.PROPERTY_NOTIFY == 0) {
                     close(link, "TX lacks Notification properties=${characteristic.properties}"); return@dispatch
                 }
-                val controlProperties = BluetoothGattCharacteristic.PROPERTY_WRITE or BluetoothGattCharacteristic.PROPERTY_INDICATE
                 for (control in listOf(checkNotNull(link.invite), checkNotNull(link.ack))) {
+                    val controlProperties = if (control.uuid == inviteUuid)
+                        BluetoothGattCharacteristic.PROPERTY_WRITE or BluetoothGattCharacteristic.PROPERTY_INDICATE
+                    else BluetoothGattCharacteristic.PROPERTY_WRITE_NO_RESPONSE or BluetoothGattCharacteristic.PROPERTY_NOTIFY
                     if (control.properties and controlProperties != controlProperties || control.getDescriptor(cccUuid) == null) {
                         close(link, "Control characteristic invalid uuid=${control.uuid} properties=${control.properties}"); return@dispatch
                     }
@@ -414,7 +416,7 @@ object BleRadio {
                 if (!gatt.setCharacteristicNotification(characteristic, true)) {
                     close(link, "DATA local subscription refused characteristic=${characteristic.uuid}"); return@dispatch
                 }
-                log("INFO", "Client DATA configured link=$token write=without_response receive=notification mtu=${link.mtu}")
+                log("INFO", "Client DATA/ACK configured link=$token write=without_response receive=notification mtu=${link.mtu}")
                 val result = if (Build.VERSION.SDK_INT >= 33) gatt.writeDescriptor(ccc, BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE)
                     else { ccc.value = BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE; if (gatt.writeDescriptor(ccc)) 0 else -1 }
                 if (result != 0) close(link, "DATA CCC write refused status=$result")
@@ -427,8 +429,10 @@ object BleRadio {
                     if (ccc == null || !gatt.setCharacteristicNotification(characteristic, true)) {
                         close(link, "control subscription unavailable after=${descriptor.characteristic.uuid}"); return@dispatch
                     }
-                    val result = if (Build.VERSION.SDK_INT >= 33) gatt.writeDescriptor(ccc, BluetoothGattDescriptor.ENABLE_INDICATION_VALUE)
-                        else { ccc.value = BluetoothGattDescriptor.ENABLE_INDICATION_VALUE; if (gatt.writeDescriptor(ccc)) 0 else -1 }
+                    val value = if (characteristic?.uuid == inviteUuid) BluetoothGattDescriptor.ENABLE_INDICATION_VALUE
+                        else BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
+                    val result = if (Build.VERSION.SDK_INT >= 33) gatt.writeDescriptor(ccc, value)
+                        else { ccc.value = value; if (gatt.writeDescriptor(ccc)) 0 else -1 }
                     if (result != 0) close(link, "Control CCC write refused uuid=${characteristic?.uuid} status=$result")
                 } else if (descriptor.characteristic.uuid == ackUuid) { link.opened = true; emit(2, token, link.mtu, address) }
                 else close(link, "unexpected CCC completion")
@@ -458,7 +462,7 @@ object BleRadio {
             val bytes = checkNotNull(link.pending)
             val status = if (link.outgoing) {
                 val characteristic = checkNotNull(when (link.channel) { 0 -> link.rx; 1 -> link.invite; else -> link.ack })
-                val type = if (link.channel != 0) BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT
+                val type = if (link.channel == 1) BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT
                     else BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE
                 if (Build.VERSION.SDK_INT >= 33) link.gatt!!.writeCharacteristic(characteristic, bytes, type)
                 else {
@@ -467,10 +471,10 @@ object BleRadio {
                 }
             } else {
                 val characteristic = checkNotNull(when (link.channel) { 0 -> tx; 1 -> invite; else -> ack })
-                if (Build.VERSION.SDK_INT >= 33) server!!.notifyCharacteristicChanged(link.device, characteristic, link.channel != 0, bytes)
+                if (Build.VERSION.SDK_INT >= 33) server!!.notifyCharacteristicChanged(link.device, characteristic, link.channel == 1, bytes)
                 else {
                     characteristic.value = bytes
-                    if (server!!.notifyCharacteristicChanged(link.device, characteristic, link.channel != 0)) 0 else -1
+                    if (server!!.notifyCharacteristicChanged(link.device, characteristic, link.channel == 1)) 0 else -1
                 }
             }
             if (status == 0) {