A Windows Phone app from Microsoft called Phone Insider has been discovered today. The app could possibly signal that the company is preparing to launch its rumored preview version of Windows 10 for smartphones.
The short description of the app simply says:
"The Phone Insider application provides registered Windows Insiders the ability to receive pre-release OS updates on their phone, directly from Microsoft.
Unfortunately, at the moment, there's no way to sign into the app, which would suggest that it's not ready for the public to fully check out.
Microsoft already has a Preview for Developers app for Windows Phone 8.1 that allows users to download new builds of the OS before they are made available to wireless carriers. This new app would seem, at first glance, to be something different. However, we stress that Microsoft has yet to officially state they are launching a preview version of Windows 10 for smartphones. So take this speculation (and everyone else's) with a grain of salt.