Older versions of the Skype desktop app for Linux will no longer work
from July 1 this year, Skype has said.
“All Skype for Linux client version 4.3 and older will be retired on
July 1, 2017. To keep chatting, please install the latest version of
Skype for Linux,” a notice on the Skype for Linux download page reads.
To install the latest Skype, download it from here
once downloaded you can either use Gdebi to install it, or just Just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:
sudo dpkg -i skypeforlinux-64.deb