IETF RFC 4142 PDF

Classic facsimile document exchange represents both a set of technical specifications and a class of service. Previous work has replicated some of that service class as a profile within Internet mail. The current specification defines "full mode" carriage of facsimile data over the Internet, building upon that previous work and adding the remaining functionality necessary for achieving reliability and capability negotiation for Internet mail, on a par with classic T.30 facsimile. These additional features are designed to provide the highest level of interoperability with the standards-compliant email infrastructure and mail user agents, while providing a level of service that approximates what is currently enjoyed by fax users.