https://www.techradar.com/news/latest-windows-10-preview-lets-you-text-from-your-pc-via-your-phone-app

Microsoft has pushed out a couple of new preview builds for the impending Windows 10 October 2018 Update (Redstone 5) in quick succession, bringing texting functionality to the Your Phone app – plus a fresh preview for ‘skip ahead’ testers (working on the update for 19H1, due in the first half of next year) was released with some minor additions.

For the update due next month, build 17754 was deployed – which just contained bug fixes – then that was swiftly followed by build 17755 arriving for fast ring testers, which as mentioned features an improved Your Phone app for Android.