The scammers use voice over IP lines (e.g. magicjack (Ymax corporation)). This is against these companys' terms of use and can lead to termination of their contract. However only law enforcement can initiate the contact if you yourself are not a customer. Therefore, report it also to your local law enforcement agency. Ultimately this is a case for the FBI legal attache in Islamabad or Delhi. If you are really annoyed: call or write to your representative in Congress. As these scams happen all over the country maybe this will trigger a reaction (and the NSA can finally be a force for good).
Pakistani man's voice said he was IRS and said my wife is involved in lawsuit I told home to go to he'll and send me a certified letter and hung up on him---
SCAM! The IRS would NEVER use the words "misconduct" or FRAUD" in any voice message. Reporting this to local law enforcement. DO NOT FALL FOR THIS!!!!!