UPDATE:
They released a new version in August 2017 which has made this awful app even worse. I didnt think it was possible but somehow the team at skype has done it.
I don’t even know where to start. Microsoft has never gotten this app to properly work. Instead somehow they managed to petition iTunes to remove their hundreds of bad reviews and now the rating for this app has gone from 1.5 starts to 3.5 stars. When you try to call people it doesn’t connect, when people try to call you and you try to pickup the call it doesn’t work. When you call someone else it will send it straight to voicemail or refuse to connect even when said person is online. Oftentimes the messages between your computer and phone aren’t synced except suddenly on occasion it “syncs up” and then bombards me with notifications for 3 day old messages. When someone calls me on another device and I pickup, it will keep ringing on the iPhone on and on and on, no matter what you do. The list could go on, this app is a complete piece of garbage, and I encourage Microsoft to spend less time cooking their review rating here and more time fixing this terrible terrible non-functioning app we all depend on.
Freddy Lansky about Skype for iPhone, v8.3