How to get notification response from the APNS using C#

I'm creating one web api application, and I want to send notification to iOS devices.

I've tried with pushsharp, but it works fine with few devices only, while sending it to multiple devices with expired/invalid tokens its not sending notifications to all devices.

So, I'm going with following code:

public async Task pushMessage(string deviceToken, string message)
{
  int port = 2195;
  String hostname = "gateway.sandbox.push.apple.com";

  String certificatePath = "~/test.p12" // my certificate path 

  X509Certificate2 clientCertificate = new X509Certificate2(System.IO.File.ReadAllBytes(certificatePath), CommonSource.GetAppleCertificatePassword(), X509KeyStorageFlags.MachineKeySet);
  X509Certificate2Collection certificatesCollection = new X509Certificate2Collection(clientCertificate);

  TcpClient client = new TcpClient(hostname, port);
  SslStream sslStream = new SslStream(client.GetStream(), false, new RemoteCertificateValidationCallback(ValidateServerCertificate), null);
   try
  {
     sslStream.AuthenticateAsClient(hostname, certificatesCollection, SslProtocols.Tls, false);
     MemoryStream memoryStream = new MemoryStream();
     BinaryWriter writer = new BinaryWriter(memoryStream);
     writer.Write((byte)0);
     writer.Write((byte)0);
     writer.Write((byte)32);

     writer.Write(HexStringToByteArray(deviceToken.ToUpper()));    
     String payload = message.ToString(); 

     writer.Write((byte)0);
     writer.Write((byte)payload.Length);
     byte[] b1 = System.Text.Encoding.UTF8.GetBytes(payload);
     writer.Write(b1);
     writer.Flush();
     byte[] array = memoryStream.ToArray();
     sslStream.Write(array);
     sslStream.Flush();

     // Read message from the server. 
     //byte[] response = ReadMessage(sslStream);   

     client.Close();
   }
  catch (System.Security.Authentication.AuthenticationException ex)
  {
     LogError(ex.Message);
     client.Close();
  }
  catch (Exception e)
  {
    LogError(e.Message);
    client.Close();
   }            
} 

This code works exactly what I wanted.
But now I want to check response from APNS server. So I've checked with byte[] response = ReadMessage(sslStream); And ReadMessage method looks like:

private byte[] ReadMessage(SslStream sslStream)
{
    MemoryStream ms = new MemoryStream();

    byte[] buffer = new byte[1024];

    int bytes = -1;
    do
    {
        bytes = sslStream.Read(buffer, 0, buffer.Length);

        ms.Write(buffer, 0, bytes);

    } while (bytes != 0);

    return ms.ToArray();
}

But when I run this, it stuck at bytes = sslStream.Read(buffer, 0, buffer.Length); I'm not able to figure out the issue.

Can anyone tell me, what is the issue with my code?