Apple use the UDID of the device to identify the device, when I give out debug builds without going through the app store I must use the UDID to authorise your device with Apple, to get the UDID number do the following.

Plug your device into a PC/MAC and go into itunes, click on the device (you should be on the summary page), the serial number is listed click on the actuall serial number and it changes to the UDID number, on a PC right mouse click on the UDID and copy the number, on a MAC CTRL-click and then copy, create an email to me at alexwhite68@gmail.com and paste the UDID into the email and I can then set you up on the apple system and release test builds to you.