These guys sound like scammers. They make you feel like someone real is talking, but someone is actually typing in the back and the computer is making the sound just like human. They might be sccamers from overseas. Looks like they're using text to speech software. If they're calling locally why they need to use the text to speech software? I would say beware before you give out any information.

Unknown caller left no message.

No caller ID. No message left.

Unknown caller, didn't leave message.

Unknown number didn't leave message.