I got call from this number saying I'm under criminal investigation!

Yea me too, I could barely hear their voice and they claimed to be from the IRS.

Rec'd call saying my husband and I are under criminal investigation for not responding to 3 previous IRS letters concerning our taxes.  They are calling because the IRS cannot notify people by phone which I have found out is true.  They had info about line 47 tax amount-foreign taxes.  How?  Called our CPA and he said to ignore it because it is a scam.  They do answer if you call the # on the caller ID.  So I asked what exactly it was they wanted.  They said they wanted to arrange an appt. with us for an IRS agent mtg.  Of course, I laughed and said I knew they were not authorized to do this.  They then said that a subpoena for our arrest will be issued by the local Federal Gov. within 24 hrs. and we will be taken away in handcuffs.

We have received three phone messages from this "agency " that sound very similar to those reported above. threatening us with the rest due to some tax problem we were supposed to call immediately on the messages each ended saying "have a nice day".
This morning we got a call from a .gentleman' with a heavy accent saying that we were under federal investigation by an agency which he didn't disclose until we asked. When we said that we were going to call our accountant to deal with this he responded saying that we "would be arrested within the one hour" if we did not deal with him immediately.
It is clearly a phishing scam.

This is not a phishing scam.  It's extortion.  These scammers want you to give them money under false pretenses.