Unrecognised number, Multiple calls today, connection takes a while, background sounds like a call centre. No thanks!

whos this

It sounded like a call centre in the background—they just kept repeating “hello, hello, helloooo” into my voicemail. I deliberately don’t have a voicemail greeting so it seems like I’ve answered the call; usually, that prompts them to speak, which helps me figure out if it’s a call centre or not.