In 2014, Apple introduced Continuity to its line of iOS devices and Mac in a pretty amazing demo at the World Wide Developer Conference. Before that presentation, Google already launched something similar with its Babel service for communication between different devices, which was finally renamed to Google Hangouts in 2013.
In early 2015, Microsoft unveiled some of the features of Windows 10, including its messaging service that would act similar to Hangouts and Continuity. With the release of the build for Windows 10 Insider, number 14316, it seems that Windows is getting closer to the reality of Messaging Everywhere.
The idea behind this messaging service is quite simple: you start a conversation via SMS message on a mobile device and taken back from your PC without any interruption. Part of this service would be based on Skype by having the infrastructure for it, so Microsoft would be able to offer a "Messaging Everywhere" experience for Windows 10 users.
It is in the new build when we know something more about this feature than is in a development phase to implement it very soon. So when the latest build for Windows 10 Mobile is released, or the Message on Mobile app is updated, Insiders will be able to access the Messaging Everywhere experience for the first time. Until now, the Windows team has been experimenting with texting across various mobile devices with some success.
The way to access these news in relation to messages through different devices is go to the Windows Insider website, create an account and become an Insider. I know configure your equipment for "Fast Ring" and in this way you will allow you to access those builds.