I'm going to have to guess at this one because I'm not sure I understand what the problem is.
If you saying under the emulator this works and on your phone connected via usb it doesn't it's because 10.0.2.2 is a special loop back for the emulator and not the phone. Change the phone to 127.0.0.1 or give the android app the address of the asp web server.
My understanding is there is no usb tether by default under Android, but it can be done.
reverse-usb-tethering-with-android[
^] explains how it can be done.
Maybe this helps, I hope so
/Darren