This number, along with 636.323.4851 and 636.323.4680 (and a few other variants of 636.323) have been calling my phone relentlessly for the last few weeks. I never answer, and they never leave a message. As soon as I block one number, they call from another. It is likely that they are a scam within the US, but it is also just as likely that they are a boiler room operation in another country that can mask the number they call from to make it appear it is from within the US, and just auto call numbers until they get an answer.