Does phone need to be connected via USB for Entune to work?

I remember reading somewhere that not all packages support BT connectivity. My experience with the ATP on a Five is that the BT works well. No tethering data plan is needed (I don't have one). I can connect via BT to my iPhone 4S or to various iPads. The 3G/4G iPads pair to the car as a phone, whereas the wifi-only iPad pairs as a mobile music device (I don't recall exactly what the NAV unit call it, just that it doesn't see a wifi-only device as a phone).

The only issue I have had (so far) is operator error when switching between devices. The car won't automatically release a connection (i.e., iPhone) when you want to connect to a new device (i.e., iPad (or iPhone #2). There might be something I am not doing quite right but other than that the BT works on the premium NAV. I know this is perhaps an apples to oranges comparison if your base package doesn't support the same BT functionality.