It is a dealer-configurable option (unfortunately I don't think you can DIY unless you have the OBD tool). They need to use their settings tool (plugs into the OBD-II port). The settings are under the Remote Keyless menu item, under "Tone Response". The Default is "ON". The available settings are "OFF" and "ON".
See the Camry iGuide at
www.ToyotaIGuide.com under "Other Features" : "Customizable Electronic Features".
My dealer changed a bunch of settings for me for no charge right after I bought the car. The biggest one for me was the "mind of its own" AC and Recirc functions. Now, whatever I had it set on when turning off the car it will remain in that state when starting up next.
-Dan