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Called my cell phone, caller id showed "unknown", and no message was left, which tells me it's a likely scammer, but also I see several other sites say this caller is a scammer, so they're a scammer in my eyes... I've blocked them.

Quote:

caller id showed "unknown"

Which simply means that there was no name in the data base when your phone carrier looked up the CNAM portion of the Caller ID.  There could be a lot of reasons for this such as the database they used was never updated, the number is unlisted, or your phone carrier was too cheap to even bother to look the number up.

Called, no message

They called and no voice message. Then I received a text message from same number. They are getting desperate. Definitely SCAM.

Called w/o leaving a message

Caller ID, "Spam Risk", Did not leave a message.  Net search clearly ID's the number as a RoboCaller. Number now blocked.

Typical default category used for missed calls. Missed calls could be from anyone.
Scammers, telemarketers, debt collectors, pranksters, surveys, notifications, alerts, wrong number, etc. Some use neighbor spoofing so it appears that an incoming call is coming from a local number, or spoof a number from a company or a government agency that you may already know and trust. If you answer, you can find out who it is or what they want. Just be aware some may use scam scripts to try to steal your money or valuable personal information, which can be used in fraudulent activity.
https://www.fcc.gov/spoofing