We received a call from 415-528-6201 - I returned the call and it disconnected after the 4th ring. This is the second such call we received in the past month.
Got two calls today. Difficult to understand what the voice (female, sound blurred) was saying. Mentioned the officer Grey. IRS and call back, Ended with a "take care". Definitely scam. As far as I know, the IRS will first send you a letter. If they call you, they will leave a clear message with not just a phone number, but also an IRS web link.