Phone mode provides a mirror of the phone's screen that simply mimics what you do on the handset. (zdnet.com)
With CShell, full Windows 10 would look just like Windows 10 Mobile does when in phone mode, and it would scale up perfectly when in Continuum for an experience that's identical to that of a normal Windows 10 desktop. (windowscentral.com)
Toggling the speaker phone mode on and then off again sometimes removes the issue, but it's not consistent. (iphonemode.com)