An updated internet-draft is available from the IETF. This draft is a work item of the Internet Fax Working Group of the IETF.
Abstract: «An Internet FAX Gateway provides functions which translate facsimile between the general switched telephone network (GSTN) and the Internet. This document provides information on recommended behaviors for Internet FAX Gateway functions for email-based Internet Fax. In this context, an offramp means facsimile data transmission to the GSTN from the Internet, and onramp means facsimile data transmission to the Internet from the GSTN. This document covers the delivery process of data with equipment which may include Internet Fax terminals, PCs on the Internet, and Fax terminals on the GSTN.»