(registered by RFC2833, updated by RFC4733) Type name: audio Subtype name: tone Required parameters: none Optional parameters: The "rate" parameter describes the sampling rate, in Hertz. The number is written as an integer. If omitted, the default value is 8000 Hz. Encoding considerations: In the terminology defined by [8] section 4.8, this type is framed and binary. Security considerations: See Section 6, "Security Considerations", in this document. Interoperability considerations: none Published specification: this document. Applications which use this media: The tone audio subtype supports the transport of pure composite tones, for example, those commonly used in the current telephone system to signal call progress. Additional information: Magic number(s): N/A. File extension(s): N/A. Macintosh file type code(s): N/A. Person & email address to contact for further information: Tom Taylor, taylor&nortel.com. IETF AVT Working Group. Intended usage: COMMON. Restrictions on usage: This type is defined only for transfer via RTP [5]. Author: IETF Audio/Video Transport Working Group. Change controller: IETF Audio/Video Transport Working Group as delegated from the IESG.