Re: Transcoding with CallManager 3.2

joshw · ‎10-21-2002

Is it possible to setup a software based transcoder using the callmanager hardware or is a dedicated DSP resource absolutely necessary? If so, can I utilize some of the DSPs on my nm-hdv-t1 card?

gillins · ‎10-21-2002

you can not use call manager to do transcoding. you have to use a hardware based one. as for the dsp on your nm-hdv there is suposed to be some code comming out in the december time frame that will allow you to do that, share the dsp for transcoding/conference and for inbound outbound calls.

what are you trying to transcode? unless you have some of the older phones you should not really need transcoding resources since the 7900 series phones can talk multiple codecs. If you are loking to make calls g711 on one side and then 729 or lower on the wan then g711 on the other side you will get some bad call sound since multiple transcoding really kills the quality.

hope this helps

scott

joshw · ‎10-21-2002

I have a VG200 with a nm-hdv-t1 that we use for inbound and outbound calling. We have remote sites that take calls from the T1 gateway locally here and therefore need to be transcoded to preserve the g729 codec. Because of the mix of 729 and 711 across the AVVID network, we need something to translate the different codecs. I just tried the 12.1.YH code and everything worked fine except for outbound calls. With the dspfarm enabled, outbound just plain dies. Any ideas how I can make it all work?

gillins · ‎10-23-2002

it may sort of work but setting up the system like that is not supported. why don't you just set the gateway for 729 and have it talk directly to the phone at the remote site?

tim.medley · ‎10-23-2002

It doesn't sound like you need transcoding at all. Unless you have something specific that can only talk G711.

Setup the gateways to talk G729 both across the WAN and on the LAN. When a call somes into a gateway from the pstn via the T1 the call is converted from TDM to packets and then sent as G729 to other gateways and CCM. CCM and the IP Phones (are you using 79XX series?) can talk G729 to each other.

tim

Tim Medley, CCNP+Voice, CCDP, CWNA

Sr. Network Architect

VoIP Group

iReadyWorld

sgavan · ‎10-24-2002

I have an application where I need to send remote site calls to an IVR app across the WAN (G.729) but IVR only talks G.711. Also, I believe you can't do conference calls at 729 without a transcoder. If there is a way to do this without need for a dedicated VG200 trancoder (DSP farm)... I'd like to know. It would be nice to be able to use spare DSP's from another device to handle this when required.

vraut · ‎10-24-2002

Hi,

Have you tried the "voice-class codec" CLI you can give a list of codecs with preferences, with this one may not require transcoding as the gateway now is capable of speaking multiple codecs.

Regards

Viraj

paul.harrison · ‎10-25-2002

If the problem you have is the VG200 then I believe I know what the problem is.

The VG200 need IP route-cache enabled. If it is disabled the voice stream goes into some kind of black hole whereby it disappears but the VG200 still reports the streams as active and the only way to sort it out is to reset the box.

Enable IP route-cache on the box and the transcoding and conferencing sessions should work fine.

Paul

carlosclaudio.lopez · ‎10-29-2002

Hi I have Autoattendant running and only works in G711, but my remote sites are g729 and if I choose on the autoattendant to call a remote extension can;t do it because is G729 I can't do Conference and I can't do transfer, I need a transcoder but I don't have any other device to user for that, what can I do ? how the codec preference works ? it could be a solution ??