> Note that in France, telemarketing calls are already required to use specific number prefixes. This is already very useful: you can immediately tell whether a call is from a telemarketer just by looking at the number prefix.

This is useful only for the few who care enough to operate legally. I activated a white list mode that prevents any call from a number that isn't in my current phone book because there's a constant flood of calls from regular mobile numbers (prefixed 06), most likely from spoofing. The phone network is unbearable in France without a white list mode.