Hi, Two questions about SDP usage with Speex: 1) How to anounce thet DTX is enabled? 2) What is default value of 'cng' option? In latest draft it is defined as following: cng: comfort noise generation - either 'on' or 'off'. If off then silence frames will be silent; if 'on' then those frames will be filled with comfort noise. 3) What is the relation between 'vbr' and 'cng' options? Is there unacceptable combinations of them? In lastest draft 'vbr' is defined as following: vbr: variable bit rate - either 'on' 'off' or 'vad' (defaults to off). If on, variable bit rate is enabled. If off, disabled. If set to 'vad' then constant bit rate is used but silence will be encoded with special short frames to indicate a lack of voice for that period. -- Regards, Alexander Chemeris. SIPez LLC. SIP VoIP, IM and Presence Consulting http://www.SIPez.com tel: +1 (617) 273-4000