PHP Receiving SMS

<?php

$sender = $_POST['sender'];
$data = $_POST['data'];
$name = $_POST['name'];

$message = process_incoming_message($sender, $data, $name);

// plug in the values returned from
// http://api.upsidewireless.com/soap/Authentication.asmx?op=GetParameters

$token = '4289bd26-4a8c-468b-847e-1ea72fd2dfd1';
$signature = 'y5MZoN7mV0sCYZHrBFDJbPL';

$api_call_data = array(
        'token' => $token,
        'signature' => $signature,
        'recipient' => $sender, // The recipient is the recipient because we are sending right back to them
        'message' => $message,
        'encoding' => 'Seven' // Use 'Sixteen' if you are sending in Unicode
    );
    
$post_data = build_post_data($api_call_data );

// Please refer to
// http://api.upsidewireless.com/
// for other sending methods

$url = 'http://api.upsidewireless.com/soap/SMS.asmx/Send_Plain';

$xml = do_post_request($url, $post_data);

// be sure you look at the XML from above to see if there are any errors

/************* Main processing function **************/

function process_incoming_message($sender, $data, $name) {

    return 'Message Received:' . date("Y-m-d H:i:s");

}

// Everything below is just function definitions

function do_post_request($url, $data, $optional_headers = null) 
{ 
    $params = array('http' => array('method' => 'POST', 'content' => $data));
    
    if ($optional_headers !== null) { 
        $params['http']['header'] = $optional_headers; 
    }
    
    $ctx = stream_context_create($params); 
    
    $fp = @fopen($url, 'rb', false, $ctx); 
    if (!$fp) { 
        throw new Exception("Problem with $url, $php_errormsg"); 
    }
    
    $response = @stream_get_contents($fp); 
    
    if ($response === false) { 
        throw new Exception("Problem reading data from $url, $php_errormsg"); 
    }
    
    return $response; 
}


function build_post_data($data, $prefix=null, $sep='', $key='') {
    
    $ret = array();
    
    foreach((array)$data as $k => $v) {

        $k = urlencode($k);
        
        if(is_int($k) && $prefix != null) {
            $k = $prefix.$k;
        }
    
        if(!empty($key)) {
            $k = $key."[".$k."]";
        }

        if(is_array($v) || is_object($v)) {
            array_push($ret, build_post_data($v,"",$sep,$k));
        } else {
            array_push($ret,$k."=".urlencode($v));
        }
    }

    if(empty($sep)) {
        $sep = ini_get("arg_separator.output");
    }

    return implode($sep, $ret);
}

?>