<style>
.info {
  display: none;
}
</style>

<script>
$(document).ready(function(){
  $(function() {
      $("tr").click(function() {
          if ($(this).find("> .info").css('display') == 'none') {
              $(this).find("> .info").show();
          } else {
              $(this).find("> .info").hide();
          }
      });
  });
});
</script>

<table>
  <tr>
    <td>Joe Bloggs</td>
    <td>joebloggs@email.com</td>
      <div class="info">555.555.555</div>
  </tr>
    <td>Sam Doe</td>
    <td>samdoe@email.com</td>
      <div class="info">556.556.556</div>
    </tr>
</table>