SDP Extensions for Fax over IP Using T.38

Document Type Expired Internet-Draft (mmusic WG)
Authors Henning Schulzrinne  , Elin WEDLUND  , Wenyu Jiang 
Last updated 1998-12-16
Stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
Expired & archived
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Stream WG state WG Document
Document shepherd No shepherd assigned
IESG IESG state Expired
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


Fax over IP is currently using SMTP, i.e. the fax is sent as an e-mail. It would be desireable to support a fax delivery that can return status of the transmission in real time, such as whether the phone number or address was correct, whether the remote side was busy, etc. The ITU is standardizing a protocol for transferring real time fax over IP, T.38. This standard is meant to be used with the H.323 standard, but it is also possible to use it together with SIP, provided that SDP is extended to support the necessary parameters. This document defines extensions to SDP to support the use of T.38 for real-time fax.


Henning Schulzrinne (
Wenyu Jiang (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)