Got this from XDA… tried and tested… just follow the procedure: )
This app does not require you to have a rooted device in order to edit your build.prop, it will fake the phone type for you. So all android devices can avail of this offer.Just follow these few simple instructions and you will have a massive FREE 50GB box.com account.If you dont have an account
1. Go to https://www.box.com/signupor use the Box app available free on the Market here:https://market.android.com/details?id=com.box.android
2.They will send you a validation Email, accept this and you will have 5GB free.
3.Install “Free 50GB Box.com v1.1” and open it, input your email address and password (I have been assured by the dev of this app that no email address or username, is stored by the app or sent to him or anything like that, but if you are unsure, just change your password after the upgrade to 50GB using your web browser and in account settings.
4.Press “Upgrade to 50GB!!!” you will see a toast saying you have been upgraded to 50GB5.
Log into your account, either via the normal Box app or web browser and you will see you have been upgraded from 5 to 50GB!.
Enjoy this spaceCredits to redphxapk Link