(per RFC4612) MIME media type name: audio MIME subtype name: t38 Required parameters: rate: The RTP timestamp clock rate, which SHOULD be 8000Hz. The clock frequency MAY be set to any value, but it SHOULD be set to the same value as that for any audio packets in the same RTP stream in order to avoid RTP timestamp rate switching. T38FaxRateManagement: Indicates the fax rate management model as defined in T.38. Values may be "localTCF" or "transferredTCF". This parameter is defined in ITU-T Recommendation T.38. Optional parameters: T38FaxFillBitRemoval: Indicates the capability to remove and insert fill bits in Phase C (refer to [6]), non-ECM data to reduce bandwidth. This is a boolean parameter (inclusion = true, exclusion = false). This parameter is defined in ITU-T Recommendation T.38. T38FaxTranscodingMMR: Indicates the ability to convert to/from MMR from/to the line format for increasing the compression of the data and reducing the bandwidth in the packet network. This is a boolean parameter (inclusion = true, exclusion = false). This parameter is defined in ITU-T Recommendation T.38. T38FaxTranscodingJBIG: Indicates the ability to convert to/from JBIG to reduce bandwidth. This is a boolean parameter (inclusion = true, exclusion = false). This parameter is defined in ITU-T Recommendation T.38. T38FaxVersion: This is the version number of ITU-T Rec. T.38. New versions shall be compatible with previous versions. Absence of this parameter indicates version 0. The version is expressed as an integer value. This parameter is defined in ITU-T Recommendation T.38. T38FaxMaxBuffer: Indicates the maximum number of octets that can be stored on the remote device before an overflow condition occurs. It is the responsibility of the transmitting application to limit the transfer rate to prevent an overflow. The negotiated data rate should be used to determine the rate at which data is being removed from the buffer. Value is an integer. This parameter is defined in ITU-T Recommendation T.38. T38FaxMaxDatagram: The maximum size of the payload within an RTP packet that can be accepted by the remote device. This is an integer value. This parameter is defined in ITU-T Recommendation T.38. Encoding considerations: The encoding of the IFP RTP packets is defined in ITU-T Recommendation T.38. This sub-type is not intended for use with e-mail. Security considerations: See Section 6 of RFC 4612. Interoperability considerations: ITU-T Recommendation T.38 defines the procedures, syntax, and parameters for the carriage of T.38 over RTP within the context of H.323 [8], SIP [9], and H.248 [7] systems. Published specification: ITU-T Recommendation T.38, "Procedures for real-time Group 3 facsimile communication over IP networks", September 2005 Applications which use this media type: Real-time facsimile (fax) Additional information: Magic number(s): File extension(s): Macintosh File Type Code(s): Person & email address to contact for further information: Paul E. Jones paulej&packetizer.com Intended usage: COMMON Author/Change controller: Paul E. Jones