%% You should probably cite rfc3389 instead of this I-D.
@techreport{ietf-avt-rtp-cn-06,
    number =    {draft-ietf-avt-rtp-cn-06},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-ietf-avt-rtp-cn/06/},
    author =    {Robert Zopf},
    title =     {{Real-time Transport Protocol (RTP) Payload for Comfort Noise (CN)}},
    pagetotal = 8,
    year =      2002,
    month =     apr,
    day =       3,
    abstract =  {This document describes an RTP {[}2{]} payload format for transporting comfort noise (CN). The CN payload type is primarily for use with audio codecs that do not support comfort noise as part of the codec itself such as ITU-T Recommendations G.711 {[}3{]}, G.726 {[}4{]}, G.727 {[}5{]}, G.728 {[}6{]}, and G.722 {[}7{]}.},
}