olark.configure('CalloutBubble.bubble_image_url_offline', 'path/to/file' );

Notes

Sets the Attention Grabber image while all your operators are set to away or offline.

Like the other Attention Grabber calls, this works on a page by page basis. You can choose an offline Attention Grabber for use across the entire site in the Attention Grabber settings

This call would be useful if you wanted a different image on a particular page, such as the contact page, or if you only wanted the Attention Grabber to appear on one page.

You would add it under the existing Olark code on the page like this:

olark.configure('CalloutBubble.bubble_image_url_offline', 'path/to/file' );