The recently released Vonage Mobile app is a solid way to make free calls from your Android smartphone with other Vonage customers and even offers a ton of free call time to anywhere in the US.
Windows 10 review: Microsoft goes back to the future
Windows 10 ISOs now available to download
Poll: Is Windows 10 ready for its launch?
Hands-on: Phone Continuum in Windows 10 Mobile
windows 10 phone continuum
Hands-on: Windows Hello biometric log-in