更改Skype按钮图像

I am using https://dev.skype.com/skype-uri/generator for skype call functionality. I want to change image of skype icon when user is offline .I am using http://mystatus.skype.com/prince.txt for status.

<script type="text/javascript" src="http://cdn.dev.skype.com/uri/skype-uri.js"></script>
    <div id="SkypeButton_Call_prince_1">
      <script type="text/javascript">
        Skype.ui({
          "name": "call",
          "element": "SkypeButton_Call_prince_1",
          "participants": ["prince"],
          "imageSize": 32
        });
      </script>
    </div>

but that code (and all the others) that is provided comes with it's own skype logo button. I'm trying to get the above to function with a custom image.

Any help would be appreciated.