This post is based on following special cable interface.
Here the schematics of the add-on box..
a) BSI problem (add the value of 2,7 or 5.1 to the actual resistor inside the cable)
b) Low power problem (using a standard usb charger you can give up to 1 ampere to the mobile ) important when you have not a self powered usb hub or you are using a laptop.
Valid solution as well (Using an UFC cable connecting only GND and VPP to the battery connector) to give power to the mobile during an USB flash.
Comments on the Project
The LOW power problem is the biggest working on mobiles like 6300, 6500, 5800, N95 or N96 where most boxes or usb ports fail to give the proper current to the mobile in restarting it and the job goes in error.
As well those mobile are the cause of problem on the boxes stressing over limit the power regulator ic.
For who thinks a 10 K resistor needs to be added I think is useless considering all the commercial cables, today, have at least 5.1 Kohm BSI value.. so 0, 2.7 and 5.1 are enough but this small project is free to be modified.