Dude is completely correct but please don't take from his description that you can't have Bluetooth to phone functionality and helmet to helmet intercom at the same time. You can. It would just require using Bluetooth connection to the phone and a wired connection between the helmets for the intercom.
The audio kit for the Nolan helmets includes the connections for this. It has the connection for the Bluetooth module along with two wired connections. One of those is an input to be taken from any other audio source (MPS, GPS, etc) while the other is for the helmet to helmet intercom. You could do helmet to helmet Bluetooth. Doing so would eliminate using the phone though.
The passenger helmet would not even need the Bluetooth module. Only the audio kit installed within it. That'd save a few dollars. If it did have the Bluetooth module, however, the passenger could pair to her own phone independently of the driver and his phone.