The Skype protocol in encrypted. Encryption has not been broken. Therefore, Trillian can not directly support Skype. The SkyLlian plugin uses the Skype API to add limited Skype support to Trillian. However, the plugin is in an early development stage and due to its concept Skype still has to run in the background. Ceruleanstudios stated that they will not support Skype until it is possible to directly integrate it with Trillian (e.g. without running Skype in the background) as this would defeat the purpose of Trillian.