What is URL Frame?
URL Frame (also known as URL masking or URL cloaking) is similar to URL Redirect except that instead of redirecting the client to your web page, the web page is displayed in a frame from our web server.
With this method, the clients' browsers will display your domain name (for example, www.mydomain.com) while they will be using your site and not the actual URL to your page (for example, http://example.wordpress.com/2008/02/19/hello-world/).
In order to set up the URL Frame feature for your domain, please refer to this article.
If you have any questions, feel free to contact our Support Team.