diff --git a/src/net/ICE/RtpIceChannel.cs b/src/net/ICE/RtpIceChannel.cs
index 9ce685ffc..e939ba155 100755
--- a/src/net/ICE/RtpIceChannel.cs
+++ b/src/net/ICE/RtpIceChannel.cs
@@ -2316,6 +2316,11 @@ private SocketError SendTurnAllocateRequest(IceServer iceServer)
             STUNAttributeConstants.TcpTransportType :
             STUNAttributeConstants.UdpTransportType));*/
 
+            allocateRequest.Attributes.Add(
+                new STUNAttribute(STUNAttributeTypesEnum.RequestedAddressFamily,
+                iceServer.ServerEndPoint.AddressFamily == AddressFamily.InterNetwork ?
+                STUNAttributeConstants.IPv4AddressFamily : STUNAttributeConstants.IPv6AddressFamily));
+
             byte[] allocateReqBytes = null;
 
             if (iceServer.Nonce != null && iceServer.Realm != null && iceServer._username != null && iceServer._password != null)
@@ -2359,6 +2364,11 @@ private SocketError SendTurnRefreshRequest(IceServer iceServer)
             //allocateRequest.Attributes.Add(new STUNAttribute(STUNAttributeTypesEnum.Lifetime, 3600));
             allocateRequest.Attributes.Add(new STUNAttribute(STUNAttributeTypesEnum.Lifetime, ALLOCATION_TIME_TO_EXPIRY_VALUE));
 
+            allocateRequest.Attributes.Add(
+                new STUNAttribute(STUNAttributeTypesEnum.RequestedAddressFamily,
+                iceServer.ServerEndPoint.AddressFamily == AddressFamily.InterNetwork ?
+                STUNAttributeConstants.IPv4AddressFamily : STUNAttributeConstants.IPv6AddressFamily));
+
             byte[] allocateReqBytes = null;
 
             if (iceServer.Nonce != null && iceServer.Realm != null && iceServer._username != null && iceServer._password != null)
@@ -2399,7 +2409,7 @@ private SocketError SendTurnCreatePermissionsRequest(string transactionID, IceSe
         {
             STUNMessage permissionsRequest = new STUNMessage(STUNMessageTypesEnum.CreatePermission);
             permissionsRequest.Header.TransactionId = Encoding.ASCII.GetBytes(transactionID);
-            permissionsRequest.Attributes.Add(new STUNXORAddressAttribute(STUNAttributeTypesEnum.XORPeerAddress, peerEndPoint.Port, peerEndPoint.Address));
+            permissionsRequest.Attributes.Add(new STUNXORAddressAttribute(STUNAttributeTypesEnum.XORPeerAddress, peerEndPoint.Port, peerEndPoint.Address, permissionsRequest.Header.TransactionId));
 
             byte[] createPermissionReqBytes = null;
 
diff --git a/src/net/STUN/STUNAttributes/STUNAddressAttribute.cs b/src/net/STUN/STUNAttributes/STUNAddressAttribute.cs
index 207ed1dd9..8e839caa4 100644
--- a/src/net/STUN/STUNAttributes/STUNAddressAttribute.cs
+++ b/src/net/STUN/STUNAttributes/STUNAddressAttribute.cs
@@ -19,19 +19,17 @@
 
 namespace SIPSorcery.Net
 {
-    public class STUNAddressAttribute : STUNAttribute
+    [Obsolete("Provided for backward compatibility with RFC3489 clients.")]
+    public class STUNAddressAttribute : STUNAddressAttributeBase
     {
-        public const UInt16 ADDRESS_ATTRIBUTE_LENGTH = 8;
-
-        public int Family = 1;      // Ipv4 = 1, IPv6 = 2.
-        public int Port;
-        public IPAddress Address;
-
-        public override UInt16 PaddedLength
-        {
-            get { return ADDRESS_ATTRIBUTE_LENGTH; }
-        }
-
+        /// <summary>
+        /// Obsolete.
+        /// <br/> For IPv6 support, please parse using
+        /// <br/> <see cref="STUNXORAddressAttribute(STUNAttributeTypesEnum, byte[], byte[])"/>
+        /// <br/> <br/>
+        /// Parses an IPv4 Address attribute.
+        /// </summary>
+        [Obsolete("Provided for backward compatibility with RFC3489 clients.")]
         public STUNAddressAttribute(byte[] attributeValue)
             : base(STUNAttributeTypesEnum.MappedAddress, attributeValue)
         {
@@ -47,6 +45,14 @@ public STUNAddressAttribute(byte[] attributeValue)
             Address = new IPAddress(new byte[] { attributeValue[4], attributeValue[5], attributeValue[6], attributeValue[7] });
         }
 
+        /// <summary>
+        /// Obsolete.
+        /// <br/> For IPv6 support, please parse using
+        /// <br/> <see cref="STUNXORAddressAttribute(STUNAttributeTypesEnum, byte[], byte[])"/>
+        /// <br/> <br/>
+        /// Parses an IPv4 Address attribute.
+        /// </summary>
+        [Obsolete("Provided for backward compatibility with RFC3489 clients.")]
         public STUNAddressAttribute(STUNAttributeTypesEnum attributeType, byte[] attributeValue)
             : base(attributeType, attributeValue)
         {
@@ -62,6 +68,14 @@ public STUNAddressAttribute(STUNAttributeTypesEnum attributeType, byte[] attribu
             Address = new IPAddress(new byte[] { attributeValue[4], attributeValue[5], attributeValue[6], attributeValue[7] });
         }
 
+        /// <summary>
+        /// Obsolete.
+        /// <br/> For IPv6 support, please parse using
+        /// <br/> <see cref="STUNXORAddressAttribute(STUNAttributeTypesEnum, byte[], byte[])"/>
+        /// <br/> <br/>
+        /// Parses an IPv4 Address attribute.
+        /// </summary>
+        [Obsolete("Provided for backward compatibility with RFC3489 clients.")]
         public STUNAddressAttribute(STUNAttributeTypesEnum attributeType, int port, IPAddress address)
             : base(attributeType, null)
         {
diff --git a/src/net/STUN/STUNAttributes/STUNAddressAttributeBase.cs b/src/net/STUN/STUNAttributes/STUNAddressAttributeBase.cs
new file mode 100644
index 000000000..6fea34308
--- /dev/null
+++ b/src/net/STUN/STUNAttributes/STUNAddressAttributeBase.cs
@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.Net;
+using System.Text;
+
+namespace SIPSorcery.Net
+{
+    public abstract class STUNAddressAttributeBase : STUNAttribute
+    {
+        /// <summary>
+        /// Obsolete.
+        /// <br/> Please use <see cref="ADDRESS_ATTRIBUTE_IPV4_LENGTH"/> or <see cref="ADDRESS_ATTRIBUTE_IPV6_LENGTH"/> instead.
+        /// <br/> <br/>
+        /// </summary>
+        [Obsolete("Default attribute length for IPv4 only.")]
+        public const UInt16 ADDRESS_ATTRIBUTE_LENGTH = 8;
+
+        public const UInt16 ADDRESS_ATTRIBUTE_IPV4_LENGTH = 8;
+        public const UInt16 ADDRESS_ATTRIBUTE_IPV6_LENGTH = 20;
+
+        protected UInt16 AddressAttributeLength = ADDRESS_ATTRIBUTE_IPV4_LENGTH;
+        protected byte[] TransactionId;
+
+        /// <summary>
+        /// Defaults to IPv4 (0x01 // 1)
+        /// </summary>
+        public int Family = 1;      // Ipv4 = 1, IPv6 = 2.
+        public int Port;
+        public IPAddress Address;
+
+        public override UInt16 PaddedLength
+        {
+            get => AddressAttributeLength;
+        }
+
+        public STUNAddressAttributeBase(STUNAttributeTypesEnum attributeType, byte[] value)
+            : base(attributeType, value)
+        {
+        }
+    }
+}
diff --git a/src/net/STUN/STUNAttributes/STUNAttribute.cs b/src/net/STUN/STUNAttributes/STUNAttribute.cs
index fc23979c9..6fc997a65 100644
--- a/src/net/STUN/STUNAttributes/STUNAttribute.cs
+++ b/src/net/STUN/STUNAttributes/STUNAttribute.cs
@@ -1,4 +1,4 @@
-//-----------------------------------------------------------------------------
+//-----------------------------------------------------------------------------
 // Filename: STUNAttribute.cs
 //
 // Description: Implements STUN message attributes as defined in RFC5389.
@@ -59,6 +59,7 @@ public enum STUNAttributeTypesEnum : ushort
         ReflectedFrom = 0x000B,         // Not used in RFC5389.
         Realm = 0x0014,
         Nonce = 0x0015,
+        RequestedAddressFamily = 0x0017,// Added in RFC6156.
         XORMappedAddress = 0x0020,
 
         Software = 0x8022,              // Added in RFC5389.
@@ -97,6 +98,15 @@ public class STUNAttributeConstants
     {
         public static readonly byte[] UdpTransportType = new byte[] { 0x11, 0x00, 0x00, 0x00 };     // The payload type for UDP in a RequestedTransport type attribute.
         public static readonly byte[] TcpTransportType = new byte[] { 0x06, 0x00, 0x00, 0x00 };     // The payload type for TCP in a RequestedTransport type attribute.
+
+        /// <summary>
+        /// The requested TURN relay ip address is IPv4 (RFC5389, Section 15.1)
+        /// </summary>
+        public static readonly byte[] IPv4AddressFamily = new byte[] { 0x01, 0x00, 0x00, 0x00 };
+        /// <summary>
+        /// The requested TURN relay ip address is IPv6 (RFC5389, Section 15.1)
+        /// </summary>
+        public static readonly byte[] IPv6AddressFamily = new byte[] { 0x02, 0x00, 0x00, 0x00 };
     }
 
     public class STUNAttribute
@@ -147,7 +157,9 @@ public STUNAttribute(STUNAttributeTypesEnum attributeType, ulong value)
             Value = NetConvert.GetBytes(value);
         }
 
-        public static List<STUNAttribute> ParseMessageAttributes(byte[] buffer, int startIndex, int endIndex)
+        public static List<STUNAttribute> ParseMessageAttributes(byte[] buffer, int startIndex, int endIndex) => ParseMessageAttributes(buffer, startIndex, endIndex, null);
+
+        public static List<STUNAttribute> ParseMessageAttributes(byte[] buffer, int startIndex, int endIndex, STUNHeader header)
         {
             if (buffer != null && buffer.Length > startIndex && buffer.Length >= endIndex)
             {
@@ -194,7 +206,7 @@ public static List<STUNAttribute> ParseMessageAttributes(byte[] buffer, int star
                     }
                     else if (attributeType == STUNAttributeTypesEnum.XORMappedAddress || attributeType == STUNAttributeTypesEnum.XORPeerAddress || attributeType == STUNAttributeTypesEnum.XORRelayedAddress)
                     {
-                        attribute = new STUNXORAddressAttribute(attributeType, stunAttributeValue);
+                        attribute = new STUNXORAddressAttribute(attributeType, stunAttributeValue, header.TransactionId);
                     }
                     else if(attributeType == STUNAttributeTypesEnum.ConnectionId)
                     {
diff --git a/src/net/STUN/STUNAttributes/STUNXORAddressAttribute.cs b/src/net/STUN/STUNAttributes/STUNXORAddressAttribute.cs
index 6f90c7c6b..c6cc025c0 100644
--- a/src/net/STUN/STUNAttributes/STUNXORAddressAttribute.cs
+++ b/src/net/STUN/STUNAttributes/STUNXORAddressAttribute.cs
@@ -1,4 +1,4 @@
-//-----------------------------------------------------------------------------
+//-----------------------------------------------------------------------------
 // Filename: STUNXORAddressAttribute.cs
 //
 // Description: Implements STUN XOR mapped address attribute as defined in RFC5389.
@@ -14,6 +14,7 @@
 //-----------------------------------------------------------------------------
 
 using System;
+using System.Linq;
 using System.Net;
 using SIPSorcery.Sys;
 
@@ -23,41 +24,89 @@ namespace SIPSorcery.Net
     /// This attribute is the same as the mapped address attribute except the address details are XOR'ed with the STUN magic cookie. 
     /// THe reason for this is to stop NAT application layer gateways from doing string replacements of private IP addresses and ports.
     /// </summary>
-    public class STUNXORAddressAttribute : STUNAttribute
+    public class STUNXORAddressAttribute : STUNAddressAttributeBase
     {
-        public const UInt16 ADDRESS_ATTRIBUTE_LENGTH = 8;
-
-        public int Family = 1;      // Ipv4 = 1, IPv6 = 2.
-        public int Port;
-        public IPAddress Address;
-
-        public override UInt16 PaddedLength
+        /// <summary>
+        /// Obsolete.
+        /// <br/> For IPv6 support, please parse using
+        /// <br/> <see cref="STUNXORAddressAttribute(STUNAttributeTypesEnum, byte[], byte[])"/>
+        /// <br/> <br/>
+        /// Parses an XOR-d (encoded) IPv4 Address attribute.
+        /// </summary>
+        [Obsolete("Provided for backward compatibility with RFC3489 clients.")]
+        public STUNXORAddressAttribute(STUNAttributeTypesEnum attributeType, byte[] attributeValue)
+            : this(attributeType, attributeValue, null)
         {
-            get { return ADDRESS_ATTRIBUTE_LENGTH; }
         }
 
-        public STUNXORAddressAttribute(STUNAttributeTypesEnum attributeType, byte[] attributeValue)
+        /// <summary>
+        /// Parses an XOR-d (encoded) Address attribute with IPv4/IPv6 support.
+        /// </summary>
+        /// <param name="attributeType">of <see cref="STUNAttributeTypesEnum.XORMappedAddress"/>
+        /// or <see cref="STUNAttributeTypesEnum.XORPeerAddress"/>
+        /// or <see cref="STUNAttributeTypesEnum.XORRelayedAddress"/></param>
+        /// <param name="attributeValue">the raw bytes</param>
+        /// <param name="transactionId">the <see cref="STUNHeader.TransactionId"/></param>
+        public STUNXORAddressAttribute(STUNAttributeTypesEnum attributeType, byte[] attributeValue, byte[] transactionId)
             : base(attributeType, attributeValue)
         {
+            Family = attributeValue[1];
+            AddressAttributeLength = Family == 1 ? ADDRESS_ATTRIBUTE_IPV4_LENGTH : ADDRESS_ATTRIBUTE_IPV6_LENGTH;
+            TransactionId = transactionId;
+
+            byte[] address;
+
             if (BitConverter.IsLittleEndian)
             {
                 Port = NetConvert.DoReverseEndian(BitConverter.ToUInt16(attributeValue, 2)) ^ (UInt16)(STUNHeader.MAGIC_COOKIE >> 16);
-                UInt32 address = NetConvert.DoReverseEndian(BitConverter.ToUInt32(attributeValue, 4)) ^ STUNHeader.MAGIC_COOKIE;
-                Address = new IPAddress(NetConvert.DoReverseEndian(address));
+                address = BitConverter.GetBytes(NetConvert.DoReverseEndian(BitConverter.ToUInt32(attributeValue, 4)) ^ STUNHeader.MAGIC_COOKIE).Reverse().ToArray();
             }
             else
             {
                 Port = BitConverter.ToUInt16(attributeValue, 2) ^ (UInt16)(STUNHeader.MAGIC_COOKIE >> 16);
-                UInt32 address = BitConverter.ToUInt32(attributeValue, 4) ^ STUNHeader.MAGIC_COOKIE;
-                Address = new IPAddress(address);
+                address = BitConverter.GetBytes(BitConverter.ToUInt32(attributeValue, 4)  ^ STUNHeader.MAGIC_COOKIE);
+            }
+
+            if (Family == STUNAttributeConstants.IPv6AddressFamily[0] && TransactionId != null)
+            {
+                address = address.Concat(BitConverter.GetBytes(BitConverter.ToUInt32(attributeValue, 08) ^ BitConverter.ToUInt32(TransactionId, 0)))
+                                 .Concat(BitConverter.GetBytes(BitConverter.ToUInt32(attributeValue, 12) ^ BitConverter.ToUInt32(TransactionId, 4)))
+                                 .Concat(BitConverter.GetBytes(BitConverter.ToUInt32(attributeValue, 16) ^ BitConverter.ToUInt32(TransactionId, 8)))
+                                 .ToArray();
             }
+
+            Address = new IPAddress(address);
         }
 
+        /// <summary>
+        /// Obsolete.
+        /// <br/> For IPv6 support, please create using <see cref="STUNXORAddressAttribute(STUNAttributeTypesEnum, int, IPAddress, byte[])"/>
+        /// <br/> <br/>
+        /// Creates an XOR-d (encoded) IPv4 Address attribute.
+        /// </summary>
+        [Obsolete("Provided for backward compatibility with RFC3489 clients.")]
         public STUNXORAddressAttribute(STUNAttributeTypesEnum attributeType, int port, IPAddress address)
+            : this(attributeType, port, address, null)
+        {
+        }
+
+        /// <summary>
+        /// Creates an XOR-d (encoded) Address attribute with IPv4/IPv6 support.
+        /// </summary>
+        /// <param name="attributeType">of <see cref="STUNAttributeTypesEnum.XORMappedAddress"/>
+        /// or <see cref="STUNAttributeTypesEnum.XORPeerAddress"/>
+        /// or <see cref="STUNAttributeTypesEnum.XORRelayedAddress"/></param>
+        /// <param name="port">Allocated Port</param>
+        /// <param name="address">Allocated IPAddress</param>
+        /// <param name="transactionId">the <see cref="STUNHeader.TransactionId"/></param>
+        public STUNXORAddressAttribute(STUNAttributeTypesEnum attributeType, int port, IPAddress address, byte[] transactionId)
             : base(attributeType, null)
         {
             Port = port;
             Address = address;
+            Family = address.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork ? 1 : 2;
+            AddressAttributeLength = Family == 1 ? ADDRESS_ATTRIBUTE_IPV4_LENGTH : ADDRESS_ATTRIBUTE_IPV6_LENGTH;
+            TransactionId = transactionId;
         }
 
         public override int ToByteBuffer(byte[] buffer, int startIndex)
@@ -65,33 +114,45 @@ public override int ToByteBuffer(byte[] buffer, int startIndex)
             if (BitConverter.IsLittleEndian)
             {
                 Buffer.BlockCopy(BitConverter.GetBytes(NetConvert.DoReverseEndian((UInt16)base.AttributeType)), 0, buffer, startIndex, 2);
-                Buffer.BlockCopy(BitConverter.GetBytes(NetConvert.DoReverseEndian(ADDRESS_ATTRIBUTE_LENGTH)), 0, buffer, startIndex + 2, 2);
+                Buffer.BlockCopy(BitConverter.GetBytes(NetConvert.DoReverseEndian(AddressAttributeLength)), 0, buffer, startIndex + 2, 2);
             }
             else
             {
                 Buffer.BlockCopy(BitConverter.GetBytes((UInt16)base.AttributeType), 0, buffer, startIndex, 2);
-                Buffer.BlockCopy(BitConverter.GetBytes(ADDRESS_ATTRIBUTE_LENGTH), 0, buffer, startIndex + 2, 2);
+                Buffer.BlockCopy(BitConverter.GetBytes(AddressAttributeLength), 0, buffer, startIndex + 2, 2);
             }
 
             buffer[startIndex + 4] = 0x00;
             buffer[startIndex + 5] = (byte)Family;
 
+            var address = Address.GetAddressBytes();
+
             if (BitConverter.IsLittleEndian)
             {
-                UInt16 xorPort = Convert.ToUInt16(Convert.ToUInt16(Port) ^ (STUNHeader.MAGIC_COOKIE >> 16));
-                UInt32 xorAddress = NetConvert.DoReverseEndian(BitConverter.ToUInt32(Address.GetAddressBytes(), 0)) ^ STUNHeader.MAGIC_COOKIE;
+                UInt16 xorPort = Convert.ToUInt16(Convert.ToUInt16(Port) ^ (UInt16)(STUNHeader.MAGIC_COOKIE >> 16));
+                UInt32 xorAddress = NetConvert.DoReverseEndian(BitConverter.ToUInt32(address, 0)) ^ STUNHeader.MAGIC_COOKIE;
                 Buffer.BlockCopy(BitConverter.GetBytes(NetConvert.DoReverseEndian(xorPort)), 0, buffer, startIndex + 6, 2);
                 Buffer.BlockCopy(BitConverter.GetBytes(NetConvert.DoReverseEndian(xorAddress)), 0, buffer, startIndex + 8, 4);
             }
             else
             {
-                UInt16 xorPort = Convert.ToUInt16(Convert.ToUInt16(Port) ^ (STUNHeader.MAGIC_COOKIE >> 16));
-                UInt32 xorAddress = BitConverter.ToUInt32(Address.GetAddressBytes(), 0) ^ STUNHeader.MAGIC_COOKIE;
+                UInt16 xorPort = Convert.ToUInt16(Convert.ToUInt16(Port) ^ (UInt16)(STUNHeader.MAGIC_COOKIE >> 16));
+                UInt32 xorAddress = BitConverter.ToUInt32(address, 0) ^ STUNHeader.MAGIC_COOKIE;
                 Buffer.BlockCopy(BitConverter.GetBytes(xorPort), 0, buffer, startIndex + 6, 2);
                 Buffer.BlockCopy(BitConverter.GetBytes(xorAddress), 0, buffer, startIndex + 8, 4);
             }
 
-            return STUNAttribute.STUNATTRIBUTE_HEADER_LENGTH + ADDRESS_ATTRIBUTE_LENGTH;
+            if (Family == STUNAttributeConstants.IPv6AddressFamily[0] && TransactionId != null)
+            {
+                Buffer.BlockCopy(
+                            BitConverter.GetBytes(BitConverter.ToUInt32(address, 04) ^ BitConverter.ToUInt32(TransactionId, 0))
+                    .Concat(BitConverter.GetBytes(BitConverter.ToUInt32(address, 08) ^ BitConverter.ToUInt32(TransactionId, 4)))
+                    .Concat(BitConverter.GetBytes(BitConverter.ToUInt32(address, 12) ^ BitConverter.ToUInt32(TransactionId, 8)))
+                    .ToArray(),
+                0, buffer, startIndex + 12, 12);
+            }
+
+            return STUNAttribute.STUNATTRIBUTE_HEADER_LENGTH + PaddedLength;
         }
 
         public override string ToString()
diff --git a/src/net/STUN/STUNMessage.cs b/src/net/STUN/STUNMessage.cs
index 28e6aa840..e6ed1a02f 100644
--- a/src/net/STUN/STUNMessage.cs
+++ b/src/net/STUN/STUNMessage.cs
@@ -1,4 +1,4 @@
-//-----------------------------------------------------------------------------
+//-----------------------------------------------------------------------------
 // Filename: STUNMessage.cs
 //
 // Description: Implements STUN Message as defined in RFC5389.
@@ -86,7 +86,7 @@ public void AddXORPeerAddressAttribute(IPAddress remoteAddress, int remotePort)
 
         public void AddXORAddressAttribute(STUNAttributeTypesEnum addressType, IPAddress remoteAddress, int remotePort)
         {
-            STUNXORAddressAttribute xorAddressAttribute = new STUNXORAddressAttribute(addressType, remotePort, remoteAddress);
+            STUNXORAddressAttribute xorAddressAttribute = new STUNXORAddressAttribute(addressType, remotePort, remoteAddress, Header.TransactionId);
             Attributes.Add(xorAddressAttribute);
         }
 
@@ -100,7 +100,7 @@ public static STUNMessage ParseSTUNMessage(byte[] buffer, int bufferLength)
 
                 if (stunMessage.Header.MessageLength > 0)
                 {
-                    stunMessage.Attributes = STUNAttribute.ParseMessageAttributes(buffer, STUNHeader.STUN_HEADER_LENGTH, bufferLength);
+                    stunMessage.Attributes = STUNAttribute.ParseMessageAttributes(buffer, STUNHeader.STUN_HEADER_LENGTH, bufferLength, stunMessage.Header);
                 }
 
                 if (stunMessage.Attributes.Count > 0 && stunMessage.Attributes.Last().AttributeType == STUNAttributeTypesEnum.FingerPrint)