Stupid Question About DSP Resources

[DRAGI RADOVANOVIC]

Sorry about this question,

but I would really like to know if I need DSP resources in this scenario:

A centralized CallManager, 10 IP phones at the remote site with no need for local access (only two FXO ports for SRST), two 2600 routers in between. I would like to run g.729a, but I am not sure if I need DSP resources even in this case.

Any help is greatly apreciated.

Dragi

[jolo07310]

I dont think you need it.

If you call from IP Phone to IP Phone, they have only dsp built-in to transcode.

If you call from IP Phone to PSTN, the voice gateway has own dsp to transcode.

If you have Unity that configure only for G.711, then you need transcoder.

Please let me know if I am wrong.

Ken

[rhegde]

I think if you want to have site to site conferencing using G 729 then you need a DSP resources. Because I have PSTN gateway which does not have DSP resources for G 729 conferences.

[#4]

You will not need DSP resources.

Every IP Phone has a DSP which will do the transcoding for G729 between them.

You can create a region for the 10 IP Phones and put G711 between them (assuming you have network bandwidth at the remote site). This will take care of SRST which will be G711.

[DRAGI RADOVANOVIC]

Thanks for the answers.

The situation does change though when any form of conferencing takes place?

Dragi

[dweiner · Accepted solution]

If you want conferences to be handled at the remote site, instead of an audio stream from every phone in the conference coming over the WAN, you need dsp resources (NM-HD-2VE, NM-HDV, NM-HDV-FARM, etc.) at the remote site to handle conferencing.

If you want to use the CallManager software-based conference bridge at the main site for conferencing, you will need to either 1) use G711 across the WAN for everyone in a conference. This can be set to dynamically switch to G711 when involving the conference bridge, but you still tie up WAN bandwidth, or 2) Have a dsp resource to either transcode the G.729 streams to G.711 since the CCM software-based conference bridge can only do G,711, or use the dsp resource as a hardware-based conf. bridge that can conf. at G.729

If you are running CRS applications (call center, IP-Auto Attendant, IP-IVR, etc.) it can either only do G.711, or with the latest software either G.711 or G.729 depending on the option taken during installation, but not both. Usually these are set up for G.711 so you will need a dsp resource to do transcoding from G.729 to G.711 for these applications, if you have them.