Skype and firewalls
Your firewall may be preventing Skype from accessing your system. Follow the steps below to fix this:
1. Open your firewall.
Go to Start -> All Programs and choose your firewall software to launch it.
2. Make sure Skype is listed as an exception.
Find your Program Control panel in your firewall. Select Skype and make sure access is allowed or that it is listed as an exception in the exceptions list.
3. Restart Skype and wait two minutes for it reconnect automatically.
Check your firewall manufacturer's website for more detailed instructions on your firewall. You may also want to check the other tutorials for reference if you are having trouble with your firewall settings.
If you are still having problems connecting, view the technical information or contact your system administrator.