[zurn]

Privacy/anonymity is a basic feature of any useful personal communication mechanism as I hope you know. Snailmail supported it before the phone network, and the internet supported it after the phone network. Though maybe people have forgotten now that they've moved en masse to things like facebook (<rant elided>...)

Maybe people don't know how to select this feature when they make calls? At least in GSM based networks you can select it on a per call basis when dialing (#31# prefix).

Eg. calling in anonymous tips to your local newspaper, communicating with an annoying company you don't want calling back, etc.