EDGE is data. Slower than 3G and not capable of simultaneous voice and data.
3G, you get simultaneous voice and data on AT&T. Not on Verizon, it's either or.
Uh, there's a difference between being able to do things that are already on your phone during a call and use data while on a call. Go try to surf the internet while on a call on your Verizon phone. It won't work. It's not a feature they don't tell you about. EvDO is simply not capable of simultaneous voice and data. Period.
While in practice it is true about not having simultaneous voice and data, I've successfully done so with a Sprint A-900 after going into the service settings and switching a bit to allow it. Its not guaranteed to work, but in my experience if I was online and a call came in I would be able to take it, then when ending the call be continuing directly on the data connection. It didn't break the data connection.
The A-900 doesn't have a lot of apps for testing simultaneous browsing and voice and I don't recall if I would be able to initiate data apps when already in a call, but the call would work when on data services (which I primarily was using for tethering at the time). The data service for tethering continued as a bluetooth modem while on a phone call.
This may have something to do with the Sprint network in particular and I had a little guidance from a Sprint tech I knew.