We know Microsoft is integrating Windows 10 and Windows 10 Mobile,and now we can send SMS from PC to Windows 10 Mobile using Cortana.
In Cortana on the latest Windows 10 PC Build 10565, type or speak “send SMS” and it allows you to send SMS using Windows 10 PC to Windows 10 Mobile.
However, this feature is not available on Windows 10 Mobile Build 10549, but it will soon make away to Insiders in upcoming mobile build.
SOURCE: Winbeta