I have created a code for WordPress to integrate my custom SMS API. The API URL works fine when I type it on the URL bar; but when it in the code, the API URL will not call. So this code not working when the customer places an order:

add_action( 'woocommerce_order_status_processing','mysite_woocommerce_order_status_processing' );
function mysite_woocommerce_order_status_processing( $order_id ) {

    $billing_phone="0729424391";
    $message="yep";

    $url="http://realcam.club:9710/http/send-message?username=admin&password=admin&to=".$billing_phone."&messagetype=sms.automatic&message=".$message."'";

  $response = file_get_contents( $url );

  //print_r($response);

}