Factor is the communication tool machines that use the send and receive documents from source to destination without relying on phone calls to contacts. Help for communications with evidence is a document reference.
Fax machines are used as a communication tool - Transfer documents from origin to destination through the phone lines to contact. Allows for communication with the reference document as evidence.
Fax machine is a communication tool that is used to receive the document from origin to destination by using a telephone line in contact. Help for communication with the evidence documents for reference.