We need to popup a "Help" window to our visitors who visit our website and have spent more than 30 seconds on a page. The popup window size will be 250(width)x200(height). The content of the popup page will say "Please call us at xxx-xxx-xxxx if you have any questions".
The visitor should be allowed to close the window or after 20 seconds the popup window should disappear if no action is taken by the visitor. The popup window should not be blocked by any security software. The popup window should show in the center of the page and should scroll down if the scrollbars are used on the main page.