<?
if($_POST){
$header=$_POST['header'];
$message=$_POST['message'];
$phones=$_POST['phones'];
$smsgonder=sendSMS($header, $message, $phones);
}
?>

<form action="" method="POST">
<input type="text" name="header" placeholder="Header">
<input type="text" name="message" placeholder="Message">
<input type="text" name="phones" placeholder="Phones">
<input type="submit" value="Gönder">
</form>