All you have to do is add one line of code to your template.

1.) Login to your Joomla 2.5 Administration Panel.
2.) Go to: Extensions/Template Manager
3.) Click on Templates
4.) Click on the template you are using for your website
5.) Click on 'Edit main page template'


6.) Find the following line of code:
[code type=html4strict]<jdoc:include type="head" />[/code]

7.) and add the following line:
[code type=html4strict]<meta name="SKYPE_TOOLBAR" content="SKYPE_TOOLBAR_PARSER_COMPATIBLE" />[/code]

8.) both lines will look like:
[code type=html4strict] <jdoc:include type="head" />
<meta name="SKYPE_TOOLBAR" content="SKYPE_TOOLBAR_PARSER_COMPATIBLE" />[/code]

9.) DONE!!!