It was realized several years ago that iMessage users were in a bit of a bind if they ever wished to switch to a non-Apple smartphone. Once you used iMessage with your phone number to accept messages, you were sort of stuck there. You couldn't switch to an Android phone, for example, and expect to keep getting messages - iMessage continued to get said messages, even if you weren't using iMessage. Apple released a tool to fix this - you can now de-register numbers from iMessage. Apparently they did not release said tool fast enough, as Judge Lucy Koh is on the case.