unidentified caller

I get called by this number every weekday at around 10am PST. I never answer, they never leave a message.

Caller id says "Northrup Grumman" plus this phone number.  It is NOT a Northrup Grumman telephone number, probably just another unscrupulous a**hole trying to sell air-conditioners to Alaskans.  This phone is listed as follows:
Type: Land Line
Provider: Pacific Bell
Location: Hawthorne, CA
Any additional calls and we will file a complaint with the proper authorities.  It is against federal law for a company to not provide a true identifying name.

Actually, I am pretty sure that it is Northrop Grumman.  This number shows up as the calling phone number instead of the actual extension's number when I get a call from w/in N-G.

It's definately Northrop Grumman.  It's the number that pops up when work calls me.