Techdirt discusses the lack of privacy around the Do-Not-Call list, which has been created in the US. It is possible to view other phone numbers, add numbers of others and there is no way to change mistakes.
It surely looks like a badly implemented service. This also calls for a distributed solution (RSS again), where the owner of the information can change his info when he needs. A Do-Not-Call flag can be used to define whether the user does not want to be called by telemarketeers. He could then send a ping to the central directory in order to add his feed to the central database. What rests is some way to certificate the phone number, so that can be certified the user is indeed the owner of the number (federated identity?). In the end private data will stay with it’s owner under his own control.
[see also TMCnet]