LiveID phone can be changed without doing a full factory reset.

On the desktop:

  1. Go to the website and login under the old account [email protected].
  2. Change your Windows Live ID (use any existing account or create a new one [email protected]).
  3. Save the changes and login under the new account [email protected].

On the device:

  1. Use the registry editor to the following modifications:

    “Email”[email protected]
    “User”[email protected]

    “DefaultID”[email protected]

  2. Restart the phone.

All Windows Live ID changed without a full reset!

The ID change can be made using IDswitch

PS: This way you can change only the ID, not the region, because the Microsoft billing information entered during the initial registration.