I got a letter from IRS with phone number to call to confirm my identity. Is this a legitimate request? The number to call is [removed]

[MCHinesUVA]

I received a 5071c letter after the deadline set in the letter.  They say I need a mortgage or car loan account number and I don't have those kinds of accounts.  Would they accept a debit card account?  I'm scared because I haven't received any of the stimulus checks yet but I was out of work for 5 months and need the money.

[AzzyH-21]

I got the letter, attempted to confirm online. However it stated that my credit and student loans numbers didn’t match. After checking and re-checking, I decided to just call and have been calling everyday for a at least a month and a half & can never get through. It has for sure been past the 30 day mark since receiving the letter but what am I supposed to do if no one answers the phone !? I’m tired of hearing the same old automated call -__-

—UPDATE—

I tried the call steps listed and got through to someone but they just told me that they couldn’t help me and that I needed to call the number on the form so… Yeah