how do you fix the clients outgoing port number using php?

I'm using php (the sockets extension) to handle sending and receiving xml files. I'd like to be able to fix the outgoing clients port number as the server has a set amount of incoming connections. I find that each time the php script is run it creates a new port number. The client side script I have so far is this:-

send_message('192.9.2.50','10220',$xmlCmd->asXML());

function send_message($ipaddr, $port, $msg)
{
  $fp = stream_socket_client("tcp://".$ipaddr.":".$port, $errno, $errstr);

  if (!$fp)
  {
    echo "ERR : $errno - $errstr";
  }
  else
  {开发者_JAVA技巧
    fwrite($fp,$msg);
    $response = fread($fp,1024);
    // Make a SimpleXML object from the response
    $xml = new SimpleXMLElement($response);

    echo $xml->Channel->Air->Index;

    fclose($fp);
  }
}

Update:

I'll try using file_get_contents again but the xml only seemed to pass from client to server ie no reply. Could anyone help me with the stream_context_create options, I need to combine these two but can't seem to get it right. Code:-

    $opts = array('http' => 
      array( 'method'  => 'POST',
        'header'  => 'Content-type: text/xml;',
        'content' => $msg)                             
    );
//combine with these options

$opts = array('socket'=>array('bindto'=>"192.9.2.60:2800"));

http://ilia.ws/archives/51-PHP-bind-support-via-stream-context.html

Do a basic checklist on the network level:

• Is 192.9.2.60 an IP on an actual interface on the server?
• Are there any routing or firewall rules that affect it? In Linux try ``ip route get x.x.x.x src 192.9.2.60'' and iptables -L
• Are there any other settings (eg SELinux) that interfere with PHP from binding to high ports?
• Run a sniffer and see what the server response actually says