I have this phone on the orange network. This phone is fantastic, it has a messenger which allows you send messages and pictures to other blackberry users for free.
Only problem that I had is that when I got this phone the internet would not work. Although as part of my contract with Orange I had unlimited mobile internet, Orange told me that I needed to pay an additional 5 pounds a month as blackberry uses a different type of internet to normal phones. It is connected all the time to allow emails to be recieved where as normal phones have to connect once you request it. This 'add on' included unlimited texts which is something to keep in mind if looking at it for a contract phone.