If you have a legacy Skype button on your site, it will stop working after May 2015. Legacy Skype Buttons used to let you imbed icons or buttons on your web site showing your Skype presence status (e.g. I'm online), by using an API.
These Skype buttons that showed your Skype presence were turned on by checking a box in the Windows Desktop client (In Skype > Privacy > Allow my online status to be shown on the web). You might have checked the box unknowingly, but this would have no impact on your Skype use.
We haven't actively supported these buttons for some time, as their accuracy has deteriorated. For example, someone’s status is not always reflected accurately (especially when they are on a mobile device). We are now removing their functionality entirely. However, you can replace these old buttons with the new Call and Chat buttons.
If you have a website or a blog and want to let even more people get in touch with you, you can visit the Skype buttons area to get your own customized button for your website or application.