I have the Q and a T-Mobile MDA. I am not sure who the Q is being marketed to. It's not a great phone, it's not a great PDA, and e-mail on it, well, it's no BlackBerry Killer. My 14 year old daughter thinks "it's cool" but she didn't like it much either. I put the Q behind the MDA. And the MDA is already in a drawer.... No experience with the 8125.