Hi,
What is the proper way to indicate Silence Suppression and Echo Cancelation coder
parameters in SDP? In MGCP these parameters are passed in LCO element, but for
SIP Offer/Answer model these parameters should be passed in SDP. Right?
I found RFC3108 that defines "ecan" and "silenceSupp" attributes, but it is applies
to VoATM. I wonder whether there is some standard or draft that defines similar attributes
for VoIP?
I also found that some late VoIP drafts (e.g. draft-ietf-sipping-realtimefax-00.txt) make a
use of "ecan" and "silenceSupp", referring to them as "generic SDP attributes". Does this
mean that RFC3108 attributes are now valid for VoIP too?
Also SIP-H323 IWF draft (draft-agrawal-sip-h323-interworking-01.txt) says that:
"A fmtp SDP attribute for silence suppression SHOULD be defined if
silence suppression is on."
What fmtp attribute does it refer to?
One more question - what is the current status of support for these attributes in today SIP
devices? Do you know any device that properly negotiates e.g. silence suppression mode
through the SDP?
Best regards,
Alex Agranov
---
Senior Software Engineer
COMGATES Ltd.
15 Hagalim Avenue
Herzliya, 46725
Israel
Tel. +972.9.950.0404, Ext: 228
Fax. +972.9.950.0385
Mobile. +972.54.928435
