This message implies that a firewall is blocking Skype from accessing the Internet. In that case, you should customize your firewall to allow Skype access to the Internet. Follow these steps to customize Windows firewall on your PC.
Navigate to "Start I Control Panel I Windows Firewall".

o In the dialog box that opens, click on the "General" tab.

o Now ensure that the options "On" and "Don"t allow exceptions" are unchecked.



 Click on the "Exceptions" tab.

 In the "Programs and Services" list, ensure that the check box next to Skype is checked.

However, in case Skype isn't in the list, then click on the "Add Program" button. Select Skype from the list of programs and click "OK".
On the other hand, if you're using a separate firewall such as ZoneAlarm Pro, then follow these steps to prevent it from blocking Skype from accessing the Internet.

o In ZoneAlarm Pro, click on the "Program Control" tab.

o Under "Programs", look for Skype in the list.

o Under the vertical column "Server", check if there is a tick
mark corresponding to Skype. If not, then right-click in the box and select "Allow".

o You can also select "Allow" for the other options corresponding to Skype. However, select "Block" !crossl under the column "Send mail".