I have Verizon and am confused on how blackberry's work versus regular cell phones. If you turn off internet access on a blackberry, you cannot make phone calls or text messages. Why is this? Does their internet function on a different frequency? Can anyone explain how a blackberry works?

You can still make calls. And you can text. Calls and Text use the 1X network. MMS and blackberry's browser uses the Evdo network. All carriers make you have the data plan because it's a way for them to make money. So when you buy a smart phone you have to get a data plan. But with Blackberry the phone needs to talk to the RIM network to work correctly. Verizon gives you the pipe to Rim.
Some functions in the phone like visual voice mail has to have EVDO.
For the most part the internet is on the same frequency band as voice but on a separate channel. Voice might be on channel (frequency) 1, 2, &3 Evdo might be on 6, 7&8. In some areas they might use voice on 850 and Evdo might be on PCS 1900Mhz band. Or the other way around.

Assuming VZW BB's have the same options, you're probably turning All Connections Off (via Manage Connections) instead of turning Data Services Off (via Options->Mobile Network).

Turn All Connections Off disables the radio so the BB can't transmit or receive and it will affect both voice and data. Data Services Off disables only data.

Thank for your info