(registered by RFC2833, updated by RFC4733) Type name: audio Subtype name: telephone-event Required parameters: none. Optional parameters: The "events" parameter lists the events supported by the implementation. Events are listed as one or more comma-separated elements. Each element can be either a single integer providing the value of an event code or an integer followed by a hyphen and a larger integer, presenting a range of consecutive event code values. The list does not have to be sorted. No white space is allowed in the argument. The union of all of the individual event codes and event code ranges designates the complete set of event numbers supported by the implementation. If the "events" parameter is omitted, support for events 0-15 (the DTMF tones) is assumed. 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 telephone-event audio subtype supports the transport of events occurring in telephone systems over the Internet. 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.