jabsnyder - You have the RG in a closet. You do not want to put the fax machine in that closet. So, your phone must not be in that closet.

How do you get from the RG to the phone? Do you have dial tone at other jacks in the building?

Any jack with dial tone can be used directly for fax or split for dual use. Doesn't the fax machine have two jacks? One for line & one for phone?

If a fax machine kills service when connected as above can you check options? Maybe the jack is not wired correctly? May be the fax is faulty?