Yes, you can have BIS & BES. BES for the corporate exchange email, calendar, contacts, etc and BIS to poll your POP3 accounts.
You may not be seeing enterprise activation because of your carrier or the icon is hidden. Some carrier's have different plans for BIS & BES. So the basic plan will only allow BIS, another plan will offer both.
Originally Posted by Qui-Gon Jinn (Star Wars Episode 1)
"The ablilty to speak does not make you intelligent!"