Does your Application include services such as Network Address translation? If not, then the phone will reject any FTP request, as there is no FTP server on the phone. The "Repeater application" must be able to tell incoming connections to go to a forwarding address, in this case it is the laptop IP address. So, lets say that your "repeater application" does provide NAT, then what you would do is open a browser window on your phone, and go to ipchicken.com. Use that address as your ftp server address. Once again, your "repeater" must provide NAT in order for this to work.