You can take a company discount on the voice part of the plan, not the data or the iPhone.
My wife’s company offers 15% off of the voice, my company only offers 8%, so there is a lot of variance.
There is now also a fee ($29 I think, starting in August of last year) to apply the discount.
You will probably have to call to get the discount if the person who signs you up doesn’t know how to apply it (I’d recommend signing up online to ensure you get the discount)
You can check at the following address, they will send an e-mail to your work/school email with a link to their store with the percentage discount applied:
