I work in a “call centre” environment and am just one of many in the open space. I have a very hard time focusing sometimes. I can be there and all of a sudden I’ve latched on to a conversation someone is having or hear my name. I’m at the point of tring to find a headset that has the bigger, over the ear headphone style… things. I’m half tempted to take an old pair of my big headphones, built the headset into them. Of course I’ll leave the original speakers in too.. background music for a soundtrack of the day 
All in all I’m lucky to still be there. It’s closing in on 8 years and I’ve been written up for being late too much, not meeting my sales goals (I’m a technical Support Rep for an Internet Registrar/hosting company) and so on. I’ve been out on stress leave, been absolutely miserable to loving being there and able to be far above anyone else. But that last bit is rare.
I say keep at it. If your employer needs to be educated as to what you face, DO IT. I’m getting all the paper work done for HR and my Manager. Once it’s officially documented on file it’ll be something they have to learn about. Once they get past the misconception that ADD is just not paying attention to your tasks they’ll come around.
As for hiring practices, an employer is not allowed to ask about disabilities and the like. Correct me if I’m wrong tho.
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