Do Not Call restrictions are violated every day, most often by companies and individuals who repeatedly and blatantly ignore the Do Not Call list. They use caller id blocking so that their phone numbers can't be reported to the Do Not Call registry, thus thumbing their collective noses at their victims and the law.
Technology exists for the phone companies to provide a code that can be keyed by the recipients of such calls, to identify the calls and callers as undesirable. The phone company has the calling phone number and identity of the abusers and can record the abusers' violations. Violators with high numbers of abuses can be reported to the Do Not Call registry for legal action.