Got a call at work from this number, said he wanted my cell phone number when I told him no he said he was going to F*#% me and then kill me.  He called my work number no less than 30 times in less than an hour, told him to stop and he's still calling.  The called id shows 000, but a couple of times it showed an actual number one was a 612 area code and also the 281-515-0615 number.  Pretty sure the callers are not even in the US.