In my workplace, the internet connection is through a proxy server. With Skype, I was able to talk to people in my contact list, but I was not able to add new contact. The problem and some solutions have been posted in the Skype community forum. However none of the solutions works on my Skype installation. Finally I found a way to add contact:
1. In Skype, go to Contacts -> “Import Contacts”. It will ask you for username and password for the proxy server.
2. Enter your username and password.
3. Now go to Contacts -> “Add Contact”. You should be able to add contact now.