Okay. So what are you going to do about it?
Chances are if Twitter (or Facebook, for that matter) is blocked at your company then the person who made that decision almost certainly doesn’t use Twitter and is therefore completely ignorant about the benefits.
Don’t just accept it – educate them.
Of course, you have to understand the difference between using Twitter productively and goofing around, and be able to demonstrate that effectively.
Because if YOU don’t know, how can you possibly expect them to?