Installing Win10 to winphone

[ShaneC]

Will it be possible to install W10 over W8.1, that's now installed on my Winphone, via my computer when it is finally released using the USB port?

I have only just received the Phone today, as a birthday present. The reason I ask is the cost of the download of win10 through my telco.

The winphone is a Microsoft Lumia 640 LTE

 

[Trouble]

The reason I ask is the cost of the download of win10 through my telco.

The only means, that I know of, to avoid those costs would be to connect to a WiFi network with your phone to accomplish the upgrade. IF you do not have that option as a resource you may need to resort to a "trusted" wireless network from a local institution (local library or school) or perhaps a local business where you're comfortable using their wifi network.
NOTE: Windows 10 Mobile is still quite a way off in the future (latest rumors are suggesting maybe September) so there is no hurry and......
Speaking from experience I would not suggest playing with any of the Insider Program Preview Builds, given your issues with the costs associated with the downloads. Not to mention, they are very buggy right now.