WOrks great with my blackberry 7100i and I bought the case for it too.  I use it only for driving or when I'm walking around so it's good for my purposes. And it does work with the D/C feature on the Blackberry Nextell phone I just need to hold the button when I use it.  Great item; lightweight; finally figured out how to use it over my ear and now I have no problems. Highly recommended.