(RFC 4788 published January 2007, subtype last updated January 2007) Type name: audio Subtype names: EVRCB1 Required parameters: none Optional parameters: ptime: see RFC 8866. maxptime: The maximum amount of media that can be encapsulated in each packet, expressed as time in milliseconds. The time MUST be calculated as the sum of the time the media present in the packet represents. The time SHOULD be a multiple of the duration of a single codec data frame (20 msec). If not signaled, the default maxptime value MUST be 200 milliseconds. fixedrate: Indicates the EVRC-B rate of the session while in single-rate operation. Valid values include: 0.5 and 1, where a value of 0.5 indicates the 1/2 rate while a value of 1 indicates the full rate. If this parameter is not present, 1/2 rate is assumed. silencesupp: see Section 6.1 for definition. If this parameter is not present, the default value 1 MUST be assumed. dtxmax: see Section 6.1 dtxmin: see Section 6.1 hangover: see Section 6.1 Encoding considerations: This media type is framed binary data (see RFC 4288, Section 4.8) and is defined for transfer of EVRC-B-encoded data via RTP using the compact bundled format as described in RFC 4788. Security considerations: See Section 9 of RFC 4788. Interoperability considerations: none. Published specification: The EVRC-B vocoder is specified in 3GPP2 C.S0014-B [3]. Transfer method with compact bundled RTP format is specified in RFC 4788. Applications that use this media type: It is expected that many VoIP applications (as well as mobile applications) will use this type. Additional information: none Person & email address to contact for further information: Qiaobing Xie Intended usage: COMMON Restrictions on usage: This media type depends on RTP framing; hence, it is only defined for transfer via RTP (RFC 3550 [5]). Transfer within other framing protocols is not defined at this time. Author: Qiaobing Xie Change controller: IETF Audio/Video Transport working group delegated from the IESG.