Who called from 3123400255

The caller leaves a recorded message saying that they are the IRS and are going to bring criminal charges against you if you don't call the number they provide and pay what you owe.  Definitely a scam that has been around for a long time.

they people are very professional & help me to rectify my IRS pending taxes..i paid them 2500$..

A pre-emptive shill alert!

what does that mean?

I love how you put the currency designator after the number... just like they do in India!
गधे, आप एक ख़ारिज किया जाना चाहिए.