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Conferencing with G729 Codec

Dear All,

I have a scenario with a centralized CallManager (3.1) and several IP phones in Remote locations connected via Frame Relay. For the remote phones I use G729 codec for obvious reasons (Bandwidth). It seems that conferencing is not working at the remote location phones. When G711 codec is used conference works fine. Any ideas how I can get around this problem? Can conference work with G729 codec?

Appreciate your help


Community Member

Re: Conferencing with G729 Codec

Hi there,

conferencing and G.729 are working only if you use an HW conference bridge (i.e. C6500 with board WS-X6608). The conference bridge provided with callmanager is a SW conference bridge and it can support G.711 only.


Community Member

Re: Conferencing with G729 Codec

Dear Paolo,

Thanks for the reply.

Do you by any chance know if an NM-HDV-1E1 card (E1 voice card with DSP modules) can be used as a HW conference bridge?

Community Member

Re: Conferencing with G729 Codec

As far as I know the only pieces of kit capable are the Cat6k, 4k and the VG200 voice gateway.

Ive heard that Cisco are also working on a standalone DSP box.

Re: Conferencing with G729 Codec

In addition to what Paolo said, you could try building an NT box and putting the conference software onto the NT box. Then assign the conference box in call manager.

Then you can locate the conference box at the remote site and put it into the same region, and set the region to G.711 within the region but G.729 inter-region. Unless of course you are using IVR/AA when you can only use G.711 to that region.

I've not yet tried this myself but am planning to soon. You still have a problem if you want to conference in people from other regions but at least local conferences don't use the WAN, and if you only conference in 1 inter region party then you only use 80Kbps rather than N x 80 Kbps


Community Member

Re: Conferencing with G729 Codec


I think an hardware transcoder is one solution. See following url:

I am testing that solution in a lab (vg200 with nm-hdv).

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