如何将我的值拆分为10位数

I get all mobile numbers from database and convert into string. Next for to split my mobile numbers into 10,10 digits.

  <?php
      $query = mysql_query("select phone from reservation");
      $array = array();
      while($row = mysql_fetch_array($query)){           
          $test = $row['phone'];
          $test_sp=(string)$test;//convert into string
          $arr=str_split($test_sp, "10"); //break up into every 10digits
          $new_test=implode(",",$arr);
          echo $new_test;
      }
?>

OUTPUT:

`994417626199441762619944176261`

Expecting Output:

`9944176261,9944176261,9944176261`