This number 646-367-0664 was allocated to us recently by the phone company. After receiving various calls on our number I have called the phone company and reported this matter to them and got it checked up. The phone company has verified that no outgoing calls were made from 646-367-0664. It seems that somebody else has hacked the system or mapped our Caller ID and using our caller ID for making calls.

Pay attention to the last link here as it describes your problem.  Although something tells me that you are one of the scammers.

Caller ID Spoofing:

https://en.wikipedia.org/wiki/Caller_ID_spoofing
https://consumercomplaints.fcc.gov/hc/en-us/a ... ID-and-Spoofing
https://www.fcc.gov/guides/caller-id-and-spoofing
http://800notes.com/forum/ta-9f0ce767d8019be/a-different-spoofing-victim

"... by the phone company."
But why didn't you say which phone company?

What is really suspicious is that the earliest complaints about this number stopped in 2011.

Right now it is 0730 CDT on Aug 17, 2016.
Complaints began anew on this number thread less than 24 hours ago.
Or, someone could be spoofing your number to get revenge on you.

Kevin Mason -- foreign accent -- IRS scam.

Just received call from this no.  The message left by Kevin Mason was threatening and used terms like... Emforcent action...federal magistrate ... grand jury...criminal action.  It was a male with east indian accent.   This is the 2nd no I have received this type of call from.   I wish there were other call type categories...scammer...impersonating a law enforcement or government agency.  Maybe this would raise the red flag about how many law abiding US Citizens are being harassed.