This Skype 0.97 clone is called Pinto!, is fully open-source (licensed under GPL v3) with a secure networking protocol (AES 256) and has an easy to setup server.
It’s getting constantly updated and features are being added onto it (right now, calls are in works), the latest feature added (as of b1.2) is scripting (ability to write scripts and extend functionality)
It’s meant as a trip back to the 2004 times of instant messaging and with a more open design (Skype 0.97 was closed source and had a single login server hosted by Skype)
If you have any questions or suggestions, put them here, on the Discord or on Github
Github: GitHub - PintoIM/Pinto: A modernish IM client inspired by Skype 0.97
Community Discord: Pinto! Community