If the IRS needs to contact you ** they will always do it by mail first **
The FTC has a nice blog and infographic about this and other IRS SCAMs:
https://www.consumer.ftc.gov/blog/voicemail-irs-imposter
https://www.consumer.ftc.gov/articles/0519-irs-imposter-scams-infographic
These people have called me twice in two days person on the phone has a very thick accent from India I would guess and is claiming to be with the IRS they are obviously a scam because that is not how the IRS operates and even if the IRS did call me they would probably have someone who speaks English as a first language as a point of contact
I just received a call on my mobile from 213.453.9225 automated voicemail indicating the IRS has a lawsuit against me. This has to be a scam as I would receive via USPS a notification.