There is nothing special about your telephone number. Anyone can call it, accidentally or on purpose. What is special is your name associated with the phone number. If the caller does not know your name, then the caller is simply dialing all possible numbers in an (area code)+(exchange) hoping someone gullible will answer.
As these people are criminals, they do not bother to avoid calling numbers that have been registered on the Do Not Call list. You will get more calls in the future from scammers, as more criminals get autodialers and begin dialing away.
You can call these numbers if you use a pay phone. Good luck finding one.
Waits until you say something then connects to a call center operator who says they are launching a veterans job opportunities program. Caller ID says "Huntington Beach".