diff --git a/Runtime/Extensions/GuidExtensions.cs b/Runtime/Common/GuidHelper.cs
similarity index 65%
rename from Runtime/Extensions/GuidExtensions.cs
rename to Runtime/Common/GuidHelper.cs
index 2e67b560..4338cbb5 100644
--- a/Runtime/Extensions/GuidExtensions.cs
+++ b/Runtime/Common/GuidHelper.cs
@@ -5,7 +5,7 @@ namespace Backtrace.Unity.Extensions
     /// <summary>
     /// Extension for Guid class
     /// </summary>
-    public static class GuidExtensions
+    public static class GuidHelper
     {
         /// <summary>
         /// Convert long to Guid
@@ -17,5 +17,11 @@ public static Guid FromLong(long source)
             Array.Copy(BitConverter.GetBytes(source), guidData, 8);
             return new Guid(guidData);
         }
+
+        public static bool IsNullOrEmpty(string guid)
+        {
+            const string emptyGuid = "00000000-0000-0000-0000-000000000000";
+            return string.IsNullOrEmpty(guid) || guid == emptyGuid;
+        }
     }
 }
diff --git a/Runtime/Extensions/GuidExtensions.cs.meta b/Runtime/Common/GuidHelper.cs.meta
similarity index 100%
rename from Runtime/Extensions/GuidExtensions.cs.meta
rename to Runtime/Common/GuidHelper.cs.meta
diff --git a/Runtime/Model/Attributes/MachineAttributeProvider.cs b/Runtime/Model/Attributes/MachineAttributeProvider.cs
index f15d9313..ab7f2315 100644
--- a/Runtime/Model/Attributes/MachineAttributeProvider.cs
+++ b/Runtime/Model/Attributes/MachineAttributeProvider.cs
@@ -3,21 +3,20 @@
 using System;
 using System.Collections.Generic;
 using System.Globalization;
-using System.Linq;
-using System.Net.NetworkInformation;
 using UnityEngine;
 
 namespace Backtrace.Unity.Model.Attributes
 {
     internal sealed class MachineAttributeProvider : IScopeAttributeProvider
     {
+        private readonly MachineIdStorage _machineIdStorage = new MachineIdStorage();
         public void GetAttributes(IDictionary<string, string> attributes)
         {
             if (attributes == null)
             {
                 return;
             }
-            attributes["guid"] = GenerateMachineId();
+            attributes["guid"] = _machineIdStorage.GenerateMachineId();
             IncludeGraphicCardInformation(attributes);
             IncludeOsInformation(attributes);
         }
@@ -83,35 +82,5 @@ private void IncludeGraphicCardInformation(IDictionary<string, string> attribute
             attributes["graphic.shader"] = SystemInfo.graphicsShaderLevel.ToString(CultureInfo.InvariantCulture);
             attributes["graphic.topUv"] = SystemInfo.graphicsUVStartsAtTop.ToString(CultureInfo.InvariantCulture);
         }
-
-        private string GenerateMachineId()
-        {
-#if !UNITY_WEBGL && !UNITY_SWITCH
-            // DeviceUniqueIdentifier will return "Switch" on Nintendo Switch
-            // try to generate random guid instead
-            if (SystemInfo.deviceUniqueIdentifier != SystemInfo.unsupportedIdentifier)
-            {
-                return SystemInfo.deviceUniqueIdentifier;
-            }
-            var networkInterface =
-                 NetworkInterface.GetAllNetworkInterfaces()
-                    .FirstOrDefault(n => n.OperationalStatus == OperationalStatus.Up);
-
-            PhysicalAddress physicalAddr = null;
-            string macAddress = null;
-            if (networkInterface == null
-                || (physicalAddr = networkInterface.GetPhysicalAddress()) == null
-                || string.IsNullOrEmpty(macAddress = physicalAddr.ToString()))
-            {
-                return Guid.NewGuid().ToString();
-            }
-
-            string hex = macAddress.Replace(":", string.Empty);
-            var value = Convert.ToInt64(hex, 16);
-            return GuidExtensions.FromLong(value).ToString();
-#else
-            return Guid.NewGuid().ToString();
-#endif
-        }
     }
 }
diff --git a/Runtime/Model/MachineIdStorage.cs b/Runtime/Model/MachineIdStorage.cs
new file mode 100644
index 00000000..07dfc973
--- /dev/null
+++ b/Runtime/Model/MachineIdStorage.cs
@@ -0,0 +1,112 @@
+using Backtrace.Unity.Extensions;
+using System;
+using System.Linq;
+using System.Net.NetworkInformation;
+using UnityEngine;
+
+[assembly: System.Runtime.CompilerServices.InternalsVisibleTo("Backtrace.Unity.Tests.Runtime")]
+namespace Backtrace.Unity.Model
+{
+    /// <summary>
+    /// Backtrace Machine Id storage
+    /// </summary>
+    internal class MachineIdStorage
+    {
+        /// <summary>
+        /// Player prefs machine identifier key
+        /// </summary>
+        internal const string MachineIdentifierKey = "backtrace-machine-id";
+
+        /// <summary>
+        /// Generate unique machine id. 
+        /// </summary>
+        /// <returns>Unique machine id Guid in a string format</returns>
+        internal string GenerateMachineId()
+        {
+            var storageMachineId = FetchMachineIdFromStorage();
+            if (!string.IsNullOrEmpty(storageMachineId))
+            {
+                return storageMachineId;
+            }
+
+#if !UNITY_WEBGL && !UNITY_SWITCH
+            var unityIdentifier = UseUnityIdentifier();
+            if (!GuidHelper.IsNullOrEmpty(unityIdentifier))
+            {
+                StoreMachineId(unityIdentifier);
+                return unityIdentifier;
+            }
+            var networkIdentifier = UseNetworkingIdentifier();
+            if (!GuidHelper.IsNullOrEmpty(networkIdentifier))
+            {
+                StoreMachineId(networkIdentifier);
+                return networkIdentifier;
+            }
+#endif
+            var backtraceRandomIdentifier = Guid.NewGuid().ToString();
+            StoreMachineId(backtraceRandomIdentifier);
+            return backtraceRandomIdentifier;
+        }
+
+
+        /// <summary>
+        /// Fetch a machine id in the internal storage
+        /// </summary>
+        /// <returns>machine identifier in the GUID string format</returns>
+        private string FetchMachineIdFromStorage()
+        {
+            return PlayerPrefs.GetString(MachineIdentifierKey);
+        }
+
+        /// <summary>
+        /// Set a machine id in the internal storage
+        /// </summary>
+        /// <param name="machineId">machine identifier</param>
+        private void StoreMachineId(string machineId)
+        {
+            PlayerPrefs.SetString(MachineIdentifierKey, machineId);
+        }
+
+        /// <summary>
+        /// Use Unity device identifier to generate machine identifier
+        /// </summary>
+        /// <returns>Unity machine identifier if the device identifier is supported. Otherwise null</returns>
+        protected virtual string UseUnityIdentifier()
+        {
+            if (SystemInfo.deviceUniqueIdentifier == SystemInfo.unsupportedIdentifier)
+            {
+                return null;
+            }
+            return SystemInfo.deviceUniqueIdentifier;
+        }
+
+        /// <summary>
+        /// Use Networking interface to generate machine identifier - MAC number from the networking interface.
+        /// </summary>
+        /// <returns>Machine id - MAC in a GUID format. If the networking interface is not available then it returns null.</returns>
+        protected virtual string UseNetworkingIdentifier()
+        {
+            var interfaces = NetworkInterface.GetAllNetworkInterfaces()
+                .Where(n => n.OperationalStatus == OperationalStatus.Up);
+
+            foreach (var @interface in interfaces)
+            {
+                var physicalAddress = @interface.GetPhysicalAddress();
+                if (physicalAddress == null)
+                {
+                    continue;
+                }
+                var macAddress = physicalAddress.ToString();
+                if (string.IsNullOrEmpty(macAddress))
+                {
+                    continue;
+                }
+                string hex = macAddress.Replace(":", string.Empty);
+                var value = Convert.ToInt64(hex, 16);
+                return GuidHelper.FromLong(value).ToString();
+            }
+
+            return null;
+        }
+    }
+}
diff --git a/Runtime/Model/MachineIdStorage.cs.meta b/Runtime/Model/MachineIdStorage.cs.meta
new file mode 100644
index 00000000..42a898c5
--- /dev/null
+++ b/Runtime/Model/MachineIdStorage.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 50e9d7c1eceeffe4891e61ccc4eff2e5
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Tests/Runtime/Client/BacktraceAttributeMachineIdTests.cs b/Tests/Runtime/Client/BacktraceAttributeMachineIdTests.cs
new file mode 100644
index 00000000..db7aac69
--- /dev/null
+++ b/Tests/Runtime/Client/BacktraceAttributeMachineIdTests.cs
@@ -0,0 +1,98 @@
+using Backtrace.Unity.Extensions;
+using Backtrace.Unity.Model;
+using Backtrace.Unity.Tests.Runtime.Client.Mocks;
+using NUnit.Framework;
+using UnityEngine;
+
+namespace Backtrace.Unity.Tests.Runtime.Client
+{
+    class BacktraceAttributeMachineIdTests
+    {
+        [SetUp]
+        public void Cleanup()
+        {
+            PlayerPrefs.DeleteKey(MachineIdStorage.MachineIdentifierKey);
+        }
+
+        [Test]
+        public void TestMachineAttributes_ShouldUseUnityIdentifier_ShouldReturnUnityIdentitfier()
+        {
+            var machineIdStorage = new MachineIdStorageMock();
+
+            var machineId = machineIdStorage.GenerateMachineId();
+
+            Assert.IsFalse(GuidHelper.IsNullOrEmpty(machineId));
+        }
+
+        [Test]
+        public void TestMachineAttributes_ShouldUseMac_ShouldReturnNetowrkingIdentifier()
+        {
+            var machineIdStorage = new MachineIdStorageMock(false);
+
+            var machineId = machineIdStorage.GenerateMachineId();
+
+            Assert.IsFalse(GuidHelper.IsNullOrEmpty(machineId));
+        }
+
+        [Test]
+        public void TestMachineAttributes_ShouldUseRandomMachineId_ShouldReturnRandomMachineId()
+        {
+            var machineIdStorage = new MachineIdStorageMock(false, false);
+
+            var machineId = machineIdStorage.GenerateMachineId();
+
+            Assert.IsFalse(GuidHelper.IsNullOrEmpty(machineId));
+        }
+
+        [Test]
+        public void TestMachineAttributes_ShouldAlwaysReturnTheSameValueUnityId_IdentifierAreTheSame()
+        {
+            var firstMachineIdStorage = new MachineIdStorageMock().GenerateMachineId();
+            var secGenerationOfMachineIdStorage = new MachineIdStorageMock().GenerateMachineId();
+
+            Assert.IsTrue(firstMachineIdStorage == secGenerationOfMachineIdStorage);
+        }
+
+        [Test]
+        public void TestMachineAttributes_ShouldAlwaysReturnTheSameValueMacId_IdentifierAreTheSame()
+        {
+            var firstMachineIdStorage = new MachineIdStorageMock(false).GenerateMachineId();
+            var secGenerationOfMachineIdStorage = new MachineIdStorageMock(false).GenerateMachineId();
+
+            Assert.IsTrue(firstMachineIdStorage == secGenerationOfMachineIdStorage);
+        }
+
+        [Test]
+        public void TestMachineAttributes_ShouldAlwaysReturnTheSameValueRandomId_IdentifierAreTheSame()
+        {
+            var firstMachineIdStorage = new MachineIdStorageMock(false, false).GenerateMachineId();
+            var secGenerationOfMachineIdStorage = new MachineIdStorageMock(false, false).GenerateMachineId();
+
+            Assert.IsTrue(firstMachineIdStorage == secGenerationOfMachineIdStorage);
+        }
+
+        [Test]
+        public void TestMachineAttributes_ShouldAlwaysGenerateTheSameUntiyAttribute_ShouldReturnTheSameUnityIdentitfier()
+        {
+            var machineIdStorage = new MachineIdStorageMock();
+
+            var machineId = machineIdStorage.GenerateMachineId();
+            PlayerPrefs.DeleteKey(MachineIdStorage.MachineIdentifierKey);
+            var machineIdAfterCleanup = machineIdStorage.GenerateMachineId();
+
+            Assert.AreEqual(machineId, machineIdAfterCleanup);
+        }
+
+        [Test]
+        public void TestMachineAttributes_ShouldAlwaysGenerateTheSameMacAttribute_ShouldReturnTheSameMacIdentitfier()
+        {
+            var machineIdStorage = new MachineIdStorageMock(false);
+
+            var machineId = machineIdStorage.GenerateMachineId();
+            PlayerPrefs.DeleteKey(MachineIdStorage.MachineIdentifierKey);
+            var machineIdAfterCleanup = machineIdStorage.GenerateMachineId();
+
+            Assert.AreEqual(machineId, machineIdAfterCleanup);
+        }
+    }
+}
diff --git a/Tests/Runtime/Client/BacktraceAttributeMachineIdTests.cs.meta b/Tests/Runtime/Client/BacktraceAttributeMachineIdTests.cs.meta
new file mode 100644
index 00000000..2fd66370
--- /dev/null
+++ b/Tests/Runtime/Client/BacktraceAttributeMachineIdTests.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: b2cec8ad525f2b842b12d11f7bde85d4
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Tests/Runtime/Client/Mocks.meta b/Tests/Runtime/Client/Mocks.meta
new file mode 100644
index 00000000..a4d1551e
--- /dev/null
+++ b/Tests/Runtime/Client/Mocks.meta
@@ -0,0 +1,8 @@
+fileFormatVersion: 2
+guid: fd956ac43783a6b4bbc9603939fa6a8b
+folderAsset: yes
+DefaultImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Tests/Runtime/Client/Mocks/MachineIdStorageMock.cs b/Tests/Runtime/Client/Mocks/MachineIdStorageMock.cs
new file mode 100644
index 00000000..4a5760a4
--- /dev/null
+++ b/Tests/Runtime/Client/Mocks/MachineIdStorageMock.cs
@@ -0,0 +1,39 @@
+using Backtrace.Unity.Model;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Backtrace.Unity.Tests.Runtime.Client.Mocks
+{
+    internal class MachineIdStorageMock : MachineIdStorage
+    {
+        private readonly bool _allowUnityIdentifier;
+        private readonly bool _allowNetworking;
+        public MachineIdStorageMock(bool allowUnityIdentifier = true, bool allowNetworking = true) : base()
+        {
+            _allowUnityIdentifier = allowUnityIdentifier;
+            _allowNetworking = allowNetworking;
+        }
+
+
+        protected override string UseNetworkingIdentifier()
+        {
+            if (!_allowNetworking)
+            {
+                return null;
+            }
+            return base.UseNetworkingIdentifier();
+        }
+
+        protected override string UseUnityIdentifier()
+        {
+            if (!_allowUnityIdentifier)
+            {
+                return null;
+            }
+            return base.UseUnityIdentifier();
+        }
+    }
+}
diff --git a/Tests/Runtime/Client/Mocks/MachineIdStorageMock.cs.meta b/Tests/Runtime/Client/Mocks/MachineIdStorageMock.cs.meta
new file mode 100644
index 00000000..fda396ef
--- /dev/null
+++ b/Tests/Runtime/Client/Mocks/MachineIdStorageMock.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: d5e8f08a85cb6094ab6e27c6a018641e
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
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