It’s rare that a number I call from here works. Is this all just a conspiracy?
American scammers work American business hours. Well, does that mean they are legit? No, it is a tactic to appear legit. They also are aware that they don’t want a call at 3AM. So, whether they are receiving calls on a land line, computer, or cell phone they will remove the number from service.
You can verify that the number belongs to a scammer if they do not have a legit answering service.
Do they list their business hours in the message? Might be legit.
Do they ask you to leave a message with name, phone number, and other information? Not likely to be legit... no business wants a voice mailbox full of pranks and whiny customers to handle every morning. Scammers want your contact info, it is valuable to them.
Is the line dead? Out of service? Definitely a scammer... no business would respond to a customer like that.
The message is usually like their website... void of specifics and relevant content.