This has little to do with "regulated phone companies." Many of these calls are generated from foreign locations with the ability to display any caller id or phone number they choose. That phony id also is possible with calls generated within the US. Your best bet is to either add phone blocking service to your line or get an external phone blocking unit. However, unless you get a blocker with the ability to add a large amount of phone numbers to your data base, I would wait until the same number appears a second time. Otherwise you'll fill up the blocker with calls that only ID with a given number only once.
Got this call a short while ago. As I didn't recognize the number I let it go to voicemail, which caught 4 seconds of some chatter in what is definitely a call center. A male in the background saying something inaudable, and my female caller saying 'Yeah". Caller ID is most likely forged.
Got 3 calls in succession from 771-6302, caller ID shows Washington G. George Washington? Really? Wow!
4th call immediately after was 813-310-4385. Caller ID shows Wireless Caller. Got to be the same caller, the 4 calls were too close together to be random. Of course, no messages were left, so I figure the caller(s) were up to no good.