testModel buat Database

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
class Test extends CI_Controller {
    function index()
    {
        $this->load->database();
        $this->load->model('testmodel','tes');
        $a=$this->tes->listTelp();
        echo'<pre>';print_r($a);echo'</pre>';
    }

}

class testModel extends CI_Model {
    function listTelp()
    {
        $sql='select * from telepon';
         $q=$this->db->query($sql);
        $a=array();
        foreach ($q->result_array() as $row)
            {
            $a[]=$row;
        }
        return $a;
    }
}