The voice is computer-generated, female. They leave this message:
"... from IRS, Internal Revenue Services. The reason of this call is to inform you that IRS is filing lawsuit against you. To get more information on this case file, please call on our department number 402-617-4893. I repeat, 402-617-4893. Thank you."
You notice how it's non-idiomatic English, meaning they may have translated it (e.g. using google translate) from some language that doesn't use the definite article "the".