Important notice: All Skype for Linux clients version 4.3 and older will be retired on July 1, 2017. To keep chatting, please install the latest version of Skype for Linux.
https://www.skype.com/en/download-skype/skype-for-computer/
Source: http://www.omgubuntu.co.uk/2017/06/skype-4-3-linux-stop-working-july-2017
https://www.skype.com/en/download-skype/skype-for-computer/
Source: http://www.omgubuntu.co.uk/2017/06/skype-4-3-linux-stop-working-july-2017
