title: PPP connection through serial cable works on WindowsXP but doesn't work on Windows7
body: <p>I have a device that establishes PPP connection (or incoming connection in terms of Windows) through null-modem cable and then communicates with PC using TCP sockets API. </p>
  
  <p>The problem is that all works fine on WindowsXP but does not work on Windows7. As far as I understand there are some troubles with establishing PPP connection because it doesn't get to TCP socket connection.  </p>
  
  <p>Here is handshake procedure log (from communication cable properties in device manager) on WindowsXP:</p>
  
  <blockquote>
    <p>10-27-2011 14:37:04.342 - Recv: CLIENT<br>
    10-27-2011 14:37:04.342 - Interpreted response: Ring<br>
    10-27-2011 14:37:04.357 - TSP(0000): LINEEVENT: LINE_NEWCALL<br>
    10-27-2011 14:37:04.357 - TSP(0000): LINEEVENT: LINECALLSTATE_OFFERING<br>
    10-27-2011 14:37:04.357 - TSP(0000): LINEEVENT: LINEDEVSTATE_RINGING(0x1)<br>
    10-27-2011 14:37:04.545 - Recv: CLIENT<br>
    10-27-2011 14:37:04.545 - Interpreted response: Ring<br>
    10-27-2011 14:37:04.545 - TSP(0000): LINEEVENT: LINEDEVSTATE_RINGING(0x1)<br>
    10-27-2011 14:37:04.545 - TSP(0000): Accepting Call<br>
    10-27-2011 14:37:04.545 - TSP(0000): LINEEVENT: LINECALLSTATE_ACCEPTED<br>
    10-27-2011 14:37:04.545 - TSP(0000): Answering Call<br>
    10-27-2011 14:37:04.545 - Answering the call.<br>
    10-27-2011 14:37:04.545 - Send: CLIENTSERVER<br>
    10-27-2011 14:37:04.545 - Connection established at 115200bps.<br>
    10-27-2011 14:37:04.545 - Error-control off or unknown.<br>
    10-27-2011 14:37:04.545 - Data compression off or unknown.  </p>
  </blockquote>
  
  <p>and on Windows7:</p>
  
  <blockquote>
    <p>10-27-2011 13:27:30.447 - Recv: CLIENT<br>
    10-27-2011 13:27:30.447 - Interpreted response: Ring<br>
    10-27-2011 13:27:30.647 - Recv: CLIENT<br>
    10-27-2011 13:27:30.647 - Interpreted response: Ring<br>
    10-27-2011 13:27:30.847 - Recv: CLIENT<br>
    10-27-2011 13:27:30.847 - Interpreted response: Ring<br>
    10-27-2011 13:27:30.847 - Answering the call.<br>
    10-27-2011 13:27:30.857 - Send: CLIENTSERVER<br>
    10-27-2011 13:27:30.857 - Connection established at 115200bps.<br>
    10-27-2011 13:27:30.857 - Error-control off or unknown.<br>
    10-27-2011 13:27:30.857 - Data compression off or unknown.<br>
    10-27-2011 13:27:32.415 - Hanging up the modem.<br>
    10-27-2011 13:27:32.416 - Hardware hangup by lowering DTR.<br>
    10-27-2011 13:27:32.416 - 115200,8,N,1, ctsfl=1, rtsctl=2<br>
    10-27-2011 13:27:32.416 - Initializing modem.<br>
    10-27-2011 13:27:32.416 - Waiting for a call.  </p>
  </blockquote>
  
  <p>I was assuming that some needed Windows services were stopped but couldn't find which services exactly need to be started and at the first look the same services were started in both cases.</p>
  
  <p>So, does anyone know what the problem is and how can I fix it?</p>