You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allpages apcontinue="Get_Sender_Names" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="14" ns="0" title="Calculate Credits" />
      <p pageid="18" ns="0" title="Changelog" />
      <p pageid="17" ns="0" title="Delete Sscheduled SMS" />
      <p pageid="24" ns="0" title="Get Calls History" />
      <p pageid="12" ns="0" title="Get Credit Limit" />
      <p pageid="10" ns="0" title="Get Domain Info" />
      <p pageid="15" ns="0" title="Get History" />
      <p pageid="23" ns="0" title="Get Line Details" />
      <p pageid="21" ns="0" title="Get Line List" />
      <p pageid="22" ns="0" title="Get Lines List" />
    </allpages>
  </query>
</api>