What is the equivalent of BeginRead method in Netframework v4 socket - windows-phone-8

Question

In the netframework v2, the socket use the Invoke (BeginRead) method to call a method (example ReceiveMsg) as below:
client = new TcpClient();
client.Connect(SERVERIP, PORTNO);
data = new byte[client.ReceiveBufferSize];
SendMessage("hello\n");
client.GetStream().BeginRead(data, 0, System.Convert.ToInt32(client.ReceiveBufferSize), ReceiveMsg, null);
Will this method ReceiveMsg of socket always be in "Auto Mode" such that it will standby to receive the message broadcast by SocketServer?
or It is using System.Threading.Thread.Sleep() to make ReceiveMsg method always active so that it will be in ready mode to respond to when SocketServer broadcast message?
How to do this in Netframework v4 or 4.5 socket for this ReceiveMsg method as BeginRead() is no longer required.
Thanks.
Below is the code for socket in netframework v4 :http://msdn.microsoft.com/en-us/library/hh202858(v=vs.92).aspx (for WP mango/ Wp8)
Client.Connect();
Client.Send();
Client.Receive();
public string Receive()
{
//-- receive the reply from server
string response = "Receiving Operation Timeout";
// We are receiving over an established socket connection
if (_socket != null)
{
// Create SocketAsyncEventArgs context object
SocketAsyncEventArgs socketEventArg = new SocketAsyncEventArgs();
socketEventArg.RemoteEndPoint = _socket.RemoteEndPoint;
// Setup the buffer to receive the data
socketEventArg.SetBuffer(new Byte[MAX_BUFFER_SIZE], 0, MAX_BUFFER_SIZE);
// Inline event handler for the Completed event.
// Note: This even handler was implemented inline in order to make this method self-contained.
socketEventArg.Completed += new EventHandler(delegate(object s, SocketAsyncEventArgs e)
{
if (e.SocketError == SocketError.Success)
{
// Retrieve the data from the buffer
response = Encoding.UTF8.GetString(e.Buffer, e.Offset, e.BytesTransferred);
response = response.Trim('\0');
}
else
{
response = e.SocketError.ToString();
}
_clientDone.Set();
});
// Sets the state of the event to nonsignaled, causing threads to block
_clientDone.Reset();
// Make an asynchronous Receive request over the socket
_socket.ReceiveAsync(socketEventArg);
// Block the UI thread for a maximum of TIMEOUT_MILLISECONDS seconds.
// If no response comes back within this time then proceed
_clientDone.WaitOne(TIMEOUT_MILLISECONDS);
}
else
{
response = "Socket is not initialized";
}
return response;
}