G723 codec and VAD

[th4roct]

I'm finding during testing that when G723ar53/63 is used VAD functions correctly with a terminating Cisco gateway. However, when using G723r53/63, VAD does NOT kick in. Why is this?? With VAD enabled by default on a Cisco gateway, shouldn't it work with any codec??

 

[hexn]

Only the AR codec supports VAD, the R codec does not.

http://www.cisco.com/en/US/products...ts_feature_guide09186a00800b5d75.html#xtocid5

 

[th4roct]

I saw that document on Cisco's site, but there is also a doc up there that shows the bandwidths utilized by the different codecs and it compares each one (ALL the Cisco supported codecs) with and w/o VAD. Also, VAD is a on by default on a Cisco gateway and is turned off in global mode. SOOOOO, why do they talk about VAD as it relates to all codecs if on Annex A supports it? Now you see my confusion?!

 

[hexn]

There are two versions of G.723.1, Annex-A and non Annex-A. These versions do not interoperate. G.723.1 Annex-A includes a built-in IETF VAD algorithm and CNG.