My caller ID showed an Unknown number with no message left. Therefore, that = telemarketers and or scammers. Most of these are "robo calls with spoofed numbers," so reporting them does no good. NEVER give or verify personal or financial information to ANYONE who makes an unsolicited call to you!!! I "block" these numbers if they keep calling.
Persistent call from the same number. They figure you are on to them when they call you with spoofed numbers always changing and they are hoping you think it's important enough to pick up if they send the same number all the time.