If you are signed in to Skype on multiple devices (a laptop, a tablet and a smartphone) and are sending chat messages to a group of friends on your tablet, Skype will only send notifications of new messages to your tablet and not to any of your other devices. All of your other devices will remain silent. You can continue to focus on the most important thing, your conversations, without being distracted by the sounds and vibrations of all your other devices.
The novelty announced today by Microsoft to make notifications in chat rooms Skype smarter and reach all users in the coming weeks, as long as they are running the latest versions of the app. It is worth noting, however, that calls will continue to ring on all devices, thus allowing you to choose the most convenient to answer. In addition, the chat history itself will continue to be synchronized across all devices. (Skype Blogs)