You can only install programs that have been approved by Apple on your iOS device (all applications in the App Store have been approved by Apple.) So in the case of beta testing, we need to register any beta customers' UDID with apple. This is Apple's way of approving the beta application for installation.
Email Using a Free App
If you search the App Store you will find out there are plenty of applications to help you find your UDID such as UDID Tool. After you have installed the application to your device, simply email the UDID to yourself or your developer.
Copy/Paste from iTunes
- Open iTunes and connect your device.
- Under the Summary tab in the right window you will want to find the devices' name, capacity, software version, serial number, and phone number.
- Click on Serial Number to reveal the Identifier.
- Copy the Identifier to your clipboard by choosing Edit‚ Copy.
- Now that you have the Identifier copied to your clipboard, you can paste it into an email by choosing Paste under your web browsers Edit menu.