"Digium TC400B Codec Offload Board "

If I buy this card does it means that I can use g723.1 and g729 low bandwidth codecs without any lisencies for voip on asterisk box

Thats correct. The card does the transcoding between ulaw/alaw -> g.729 and ulaw/alw -> g.723. You won’t need any thing else to do this.

Doesn’t the card transcode between g.729 --> ulaw/alaw and g.723 --> ulaw/alaw also ?

that’s what he said.

Yes it happens both ways.

to baconbuttie

I have read much about echo problem with digium analog cards and I have seen that only t1/e1 cards have onboard echo cancellation-whatewer it is, so does it mean not to bother with digium analog ones and better buy quintum and such
I am actually only originating traffic for a closed group of people only and quality is everything
And I thought about other features of an * as a really hefty addons but with echo it all will be ruined

The TC400B will have nothing to do with echo since everything in and out is comepletely voip. Digium recently released a free(If you have a Digium card) high quality software based echo cancellor for their analog cards.

The documentation of the TC400B says that it does the transcoding between:

-ulaw/alaw -> g.729
-ulaw/alaw -> g.723
-g.723 -> ulaw/alaw
-g.729 -> ulaw/alaw

But what about a direct transcode from g.729 to g.723 (and viceversa)?.

g.729 UA -------> ASTERISK w/TC400B --------> g.723 UA

It seems possible because the card could do an internal transcoding chain like:

g.729 -> ulaw -> g.723

It would reduce the channels to the half (46 channels) but thats not a problem for me.
Someone tried this?