Finding Your iPhone’s Unique Identifier (UDID) with or without iTune

Apple has given developers a way to beta test iPhone applications with up-to 100 iPhones. Some developers have already started using this to their advantage by giving their software out as free public betas. However, you must supply a developer with your iPhone's UDID (unique device identifier) in order to install these "Ad-hoc" applications on your iPhone.

Each iPhone or iPod Touch has a Unique Device Identifier (UDID), which is a sequence of 40 letters and numbers that is specific to your device. It’s like a serial number but much harder to guess. It will look something like this: 2b6f0cc904d137be2e1730235f5664094b831186.

Why do we need the UDID?

Your iPhone can only install programs that are approved by Apple. Applications in the App Store have been approved by Apple for general distribution, but beta customers get to try the app before it’s in the store. We register your UDID with Apple so they can approve our application especially for your iPhone.

How do I get my UDID?

You can copy/paste your UDID from iTunes or email it directly from your device by using a free app from the App Store.

Email Using the Free App

Install and run Ad Hoc Helper. It will create an email with your UDID. Send it to nobody@example.com.

Copy/Paste from iTunes

1. Launch iTunes and connect your iPhone.
2. In the right pane, locate the information about your iPhone, including its name, capacity, software version, serial number, and phone number. 
3. Reveal the Identifier by clicking on Serial Number:.
4. Copy the Identifier to your clipboard by choosing Edit → Copy.
5. Paste the Identifier into an email to nobody@example.com (You should be able to paste into your mail program or web browser by selecting Edit → Paste).

Getting UDID without iTunes

Options
A. System profiler.... USB.....iPhone.....use the serial number

B. Install SDK 3.0, then start up xCode, select the phone on the left pane and it will give you the UDID.

C. with pc  goto system information under settings, the goto components, then usb, the you will see the iphone connected that is the 40 digit hex number

D. iphone backup is named "{UDID} - {date}"...store on PC at C:\Users\USER\AppData\Roaming\Apple COmputer\MobileSync\Backup\

E.  Go to http://www.apple.com/support/iphone/enterprise/
Install Apple's "iPhone Configuration Utility" (Windows or MAC) and it will display the UDID and allow you to export that data to a text file for easy copy & paste into your Apple Dev Portal.

Good luck!