I can't say I've ever heard of a carrier like that. Now, is it conceivable that there's a carrier that offers one plan that does have BES, but not two separate plans? Possibly.
If you have the device PIN, I'd go to the Enterprise Readiness Tool, and put in the PIN. It will tell you if it's provisioned correctly. KB21140-How to identify available BlackBerry smartphone activation methods using the BlackBerry Expert Support Center