Send SMS using GSM modem in PHP

Question

I would like to send SMS from my GSM modem. I tried to implement this using this link as reference. But my modem will not produce any response.Any help..Thanks in advance.... Here is my code snippet.. $gsm_send_sms = new gsm_send_sms();

$gsm_send_sms->init();

$status = $gsm_send_sms->my_send_message_function("+09524566775", "raja");

$gsm_send_sms->close();

//Send SMS via serial SMS modem class gsm_send_sms {

public $port = 'COM7';
public $baud = "9600";
public $debug = true;

private $fp;
private $buffer;

//Setup COM port
public function init() {

    $this->debugmsg("Setting up port: \"{$this->port} @ \"{$this->baud}\" baud");

    exec("MODE {$this->port}: BAUD={$this->baud} PARITY=N DATA=8 STOP=1", $output, $retval);

    if ($retval != 0) {
        throw new Exception('Unable to setup COM port, check it is correct');
    }

    $this->debugmsg(implode("\n", $output));

    $this->debugmsg("Opening port");

    //Open COM port
    $this->fp = fopen($this->port . ':', 'r+');

    //Check port opened
    if (!$this->fp) {
        throw new Exception("Unable to open port \"{$this->port}\"");
    }

    $this->debugmsg("Port opened");
    $this->debugmsg("Checking for responce from modem");

    //Check modem connected
    fputs($this->fp, "AT\r");

    //Wait for ok
    $status = $this->wait_reply("OK\r\n", 5);

    if (!$status) {
        throw new Exception('Did not receive responce from modem');
    }