Ask HN: Could scammers have infiltrated the IRS callback system?

We called the IRS to discuss an issue and we utilized the callback system. We entered our phone number and were told to expect a call back within 30 minutes, from a West Virginia number. I have used this system before so all this was familiar. The call came at the expected time, from the expected area code. However, it turned out to be a scam call center. How is this technically possible?