This may be National Credit Solutions / NCS Litigation in Oklahoma City, which appears to use the same illegal tactics as the South Asian fakers. If so, the one distinguishing feature is that NCS can be sued for relief by anyone taking their extortionist calls.

Official-type material on US federal collection law:
http://www.ftc.gov/os/statutes/fdcpajump.shtm
http://www.consumerfinance.gov/guidance/supervision/manual/fdcpa-narrative/

On your Husband's ex-wife's Phone?   I don't think I would be too concerned then.  First off,   They probably would be calling for your husband's ex  or blindly calling that number hoping to hit the jack pot.  But last and foremost,  THEY can't arrest anyone.... It's a scare tactic.  Don't worry about it.   Probably some little dude sitting in the back room of a coffee shop in Southern Asia,  (India) hoping to scare up a quick buck.  Scam

NCS called and left to messages for me on my husband's ex-wife's phone saying I had 2 hours to call with case number or they were going to arrest me for fraud.

A lady called about an important business matter.  She said that this was her last attempt to contact me and she would be coming to my house or place of employment to serve me a court summons for a breach of contract.  She never mentioned what company she worked for or anything.  This was the first time she called.

James Thompson from ncs called threatening to show up to my house with local authorities to arrest me and I had 2 hrs to call them back. I have no idea what they r talking about I have not received anything in mail or nothing. I just deleted the message.

Called my place of employment and threaten to go to HR to summons me to appear in court; I am currently working with debt collection agency regarding any debt they are trying to collect; the caller was very rude and would not give me a direct number she was call from but she provide this number instead  and stated I had to call back in 30 mins.  Informed them that I could not take collection calls at work.  She called back again and wanted to speak with HR--told them I had to screen the call and placed the call on hold; she hung up. I will report the call to the FTC.