Microsoft is comprehensive in their efforts with Windows 10, ensuring that the end user will get a totally new, yet family experience across PCs, Laptops, Tablets and Phones. Skype is playing a big part in this effort, as the messaging service is making the transition from standalone app to part of the Core OS itself.
Skype will come built into your communications suite across all Windows 10 devices, and you wont have to download the app seperately. The built-in Skype experience will sync its contact book with that of your phone and your email, which will let you stay connect to friends using Skype not just on Windows devices, but also on iOS, Mac, Android and more.
You will be able to send free messages over the internet either from the taskbar or from your phone using the Skype Message and all your conversations will be synced across all devices. Additionally you can instantly initiate video or voice calls from the desktop or phone when in the conversation.
If you have a phone running Windows 10, you will have the option of sending SMS messages using Skype Credit, and respond to incoming messages through actionable notifications. While in the messaging app, Skype chats will be differentiated from SMS with the classic Skype blue and users can quickly switch between SMS and Skype messaging as needed.
Skype for Windows 10 is definitely shaping up to be something exciting and we can't wait to try it out in future builds of Windows 10 on the Windows Insider Program.
source - Skype Blog