I don't answer any of these unknown calls anymore. I look them up on Google before blocking them to confirm numbers like this one are not legit. A real caller leaves voicemail. These callers never do.
Called a few minutes ago, asking for Teresa and I said there was no such person and they said nothing and hung up after a few minutes. I work for a outgoing call research firm and we do not do this sorry of thing. Regardless of what they say, block the number and report it.