Is it possible to index custom page content? I have created certain pages and blocks using web services programmatically.The content of those pages is fetched from outside the existing Drupal installation and they are not getting indexed in search results.

Is it possible to index my custom page titles and links in the search results? Or is there any other way to do this?
Yes of course you can. You can use the hook_node_update_index() for this:

function YOURMODULE_node_update_index($node) {
   // here is an example that fetches content from an url and appends it to
   // to the data that will be indexed
   $ch = curl_init();
   curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
   curl_setopt($ch, CURL_URL, "http://example.com/readme.txt");
   $content = curl_exec($ch);
   curl_close($ch);

   // return the extra content that needs to be indexed for this node
   return $content;
}


The above will of course only work if your custom pages are stored as nodes in Drupal. For instance if you have a node that is called contact which shows content generated externally, then you need to fetch the same content in hook_node_update_index() for this specific node.