Well, heres some more info. The above number 405-233-3981 is listed two ways: Nuvox Communications out of Arcadia, Ok. and Minco, Ok and also listed as Level 3 Communications,LLC out of Oklahoma City. Get this! They are the same company! These are FAX SPAMMERS. Let's all group together and file a complaint with the FCC AND the FTC and GET these inconsiderate SOB's! Where do they get off thinking they can tie up our landlines! I don't have a fax, thank God, but they don't care what time of day they call or whether it is a Saturday or weekday. Let's stop them from abusing our telephone system.
Level 3 Communications is the largest competitive local exchange carrier (i.e., alternate landline telephone company to what used to be the Bell System monopoly) in the United States. It is also a tier 1 internet service provider and supplies services wholesale to large companies such as Netflix. See:
http://en.m.wikipedia.org/wiki/Level_3_Communications
They also earned over $6 BILLION last year (2013).
I think it is unlikely that they are wasting their time and money sending you junk faxes. More likely, it is a customer of theirs who does not list their number -- or even a customer of another phone company using Level 3 Communications as a wholesaler, or perhaps someone who has nothing at all to do with Level 3 Communications because the number was ported to another telephone service provider due to number portability. (Unless you are a phone company or a law enforcement agency, that latter bit of information is going to be unavailable to you.)
And if you are not on a Level 3 Communications line yourself, it is unlikely that you will receive the correct caller ID name information, if any at all. You might see the city and state, or a name like "Level 3 Com," but that will depend on the database kept by your own phone company.