Customer service from somewhere called and didn't leave a message, so I guess it's really not important to them to contact me. Therefore, another blocked number. Spoofed number calling has been around for a long time. No rules can stop an overseas call center from spoofing a number and calling someone. Unless the communications industry (worldwide) decides to change protocol and block transmissions between countries until the source has been determined as legal. I can't imagine that happening as communications are big business. Personally, I have blocked over 2,000 numbers and will continue to block and not answer unknown numbers. If it is important, then leave a message like most legitimate companies. (just my 2 cents)
You'll have to do that yourself, either with a call blocker/app, or completely ignoring unknown calls. Nobody on here is either calling you or can stop anyone from calling anyone other than themselves.