This is certainly flagged from the marker bit. You could request 'but when there is certainly silence no packets are transmitted, so why do you want the marker little bit?' That is since intermediate RTP packets are utilized to update the background sounds level. RFC 3550 RTP July 2003 SDES: https://titusenven.blogprodesign.com/50347120/the-2-minute-rule-for-rtp-maret88