Amazon’s customer service phone number in the US is 1-888-280-4331, and you can call that number at all times of the day.

It’s important to note that customers should have a cell phone number connected to their Amazon account. Customers must enter verification codes that will be messaged to their linked contact ...

and Reddit threads to actually talk to a human over the phone. As you probably already know from trying to contact someone on Amazon's "Contact Us" page, there is no direct number to call.