If you have a corp id # & input it on the Hilton website it will bring up the same rate as your corp rate through your agency. Same if you call the 800# & tell them the name of the corp.
BTW - on the Hilton site you can plug in your corp rate & it will bring it up, but you can also ask it to display all rates & sometimes other rates are cheaper than the corp rate, such as AAA rate or weekend rate or Hilton BB rate.
Corps of course like you to use their rate cuz usually they've negotiated a decent rate & also cuz they need to meet a room quota. I go w/ whatever is cheaper - corp or otherwise. I've had times where the corp rate was fab & other times it was way higher than just off the shelf rate.
Cheers. Sharon