trying to setup a lab to simulate a centralized CCM with remote locations across a frame link. i have everything working as it should, however, i want to simulate a g729 WAN connnection between the two sites so i can use transcoding. i setup all that is necessary for the transcoding on the voice gateway and CCM. my issue is that i configured diferent regions and device pools to simulate each location. no matter what codec i change it to, all systems still communicate. (this is before i add the transcoder in CCM). im not sure if im doing it properly, but im assuming that both locations are using G711 on the LAN and then G729 on the WAN, so, without transcoding i should get a busy when i associate the devices with the appropriate device pool. Also, as a test, i have unified messaging with the default codec 711. when i change the codec on the call manager to 729, i can still access voice mail etc. im thinking i should have gotten a busy signal because of the codec mismatch..
any help would be greatly appreciated..
Depends on what the two devices in the call support. If they both support G.711 and G.729 then a Transcoder won't be invoked for a G.729 call. If one of the end devices only supports G.711 but the call is supposed to be G.729 then a Transcoder will be invoked.
IP Phones support both so your test call will need to be to a device configured to support only G.711.
well i think i had this thing all wrong..i know the ip phones support both. but i thought that if im crossing a g729 WAN link,and i try to call from a remote ip phone i should have not been connected. even though the ip phone at the remote site is 711. so then, now im a little more confused. i specify two different regions, head office- g711 and remote site- g729. and associate device pools with regions and then associated phones and gateways. so what we are saying is that although i did that, the phones are still supposed to communicate becauase they support both codecs?..then, (and this is clearly a "not so smart" question) when do i actually use the transcoding?...is it only for trunk line calls that cross the network using a different codec?. clearly i need to do some more reading....:)
CallManager will look at the REgion configuration to determine which codec should be used. If you selected to use G.729 between two Regions and you place a call between two IP Phones that are in each Region then you will end up with a G.729 call. Meaning that the RTP stream originating from each phone will be G.729. You can see this by placing a call between these two phones, once the call is up hit the "?" button twice quickly. You will see the audio stream stats including the send and receive codecs. A transcoder won't be invoked for this case.
If you have end points that support G.711 only, such as CRS, and you place a call across Regions that is configured for G.729 you will invoke the Transcoder.
You can configure and H.323 GW dial-peer to use G.711 only and place it in the head office Region. Place a call from the remote site. You should then see the transcoder get invoked. There will then be G.729 bi-directional streams between the remote phone and transcoder. There will also be bi-directional G.711 streams between the GW and transcoder.
hi i got an additional question:
which is the rule to know which device will invoke the transcoding?
My question is based on a future deployement, i will have two sites with a centralised callmanager and on each site i will have device that only support G711 codec. I configured local hardware transcoding on each site not to use the G711 codec on the WAN. which equipment will invoke the trancoding ressource to know which MRGL do i need to configure on the devices. do i need to configure on the MRGL the local or distant transcoding ressource on the phone or the G711 device?
Yes, it is allocated based on the MRGL assigned either to the device (phone) or the device pool of the phone. If you want to restrict the phone to only use the local transcoder then do not inculde the remote trascoder's MRG in the MRGL.
i think my question wasn't clear enough...
is it possible to use ressources based on the destination and not on the source of the call...
You can do your testing using CRA, it only supports one codec. Unity has build in software transcoding that's why it is working. If you simply want to know if the expected codec was negotiated, double click the "?" button on the phone while the call is active, it will display the codec used on the screen. If all of your devices are cisco phones then you do not need transcoders in your setup.
thanks a lot....configured the dial peer to use 711 and remote as default 729 and saw transcoding working....