<?
class Products 
{
    public function get(){
        return functions::mssql_escape_string_rev();
    }
}

class functions
{
    public static function mssql_escape_string_rev()
    {
        echo 'mssql_escape_string_rev';
    }
}

$p = new Products();
$p->get();
?>

mssql_escape_string_rev