P.S. By the Way.....the SAME two companies ALSO use another fax number of 307-200-0906, located out of Montana. But they are also listed as Level 3 Communications,LLC. Anybody getting fax calls on their landline from THAT one, too? They're RELATED.
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.