I just received a strange phone call

I received a call from a mobile number claiming to be from a different district office in Seoul.
They said it was strange because someone had come in with a copy of my ID and a power of attorney to request a seal certificate, so they were calling to verify my identity...
When I asked what kind of ID it was, they said it was a resident registration card.
But I haven't had a resident registration card for 30 years; I made one when I was 18 and haven't made another one since.
I told them to report it to the police and hung up.
Is this voice phishing?