Transcoding and codec confusion

[bhupender rawat]

Hi Experts,

DO we need any transcoding between two IP phones in WAN. Like if the region is set to g.729 for one location, do IP phone needs to invoke the transcoder. My thought is that IP phones over WAN will use G.729 between each other without any external (Router) DSP involvement.

Please correct me if I am wrong for following statements as well.

If the conferencing is required on Local LAN within same cluster we will need Conference resources (router DSPs)

If conference required between different clusters like remote branch phones and main office phones then Conference resource will be required (router DSP). Conference initiator local router will be used for DSP conference resources.

If you have in house conference bridge (I think unity case also) which only understand G.711, we will need transcoding resources to be defined in main office router to convert them to G.711 form communication.

Regards

Bhupender

[Ayodeji Okanlawon]

The answer is almost yes yes yes

If the region between two IP phones is set to use G729, then the phones will use g729. There wont be any need for xcoder.

Yes You will need DSP resources if you want to have a hardware conference bridge. This is the type of conference bridge that supports both g729 and g711 codec. If you want to use the software conference bridge which runs on cucm, then you dont need DSP. But note that this wont support any g729 calls.

The conference resource that is used is dependent on the MRGL of the conference innitiator. If you have a mix of phones that use G729 and G711 then it is bette to use Hardware conference bridge which requireds DSPs.

Yes, if you have only software conference bridge and you have phones on G729, then you will need a xcoder because the conf bridge only uderstand g711..So like I said its yes, yes, yes,yes

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"'Nature is too thin a screen, the glory of the omnipresent God bursts through it everywhere"-Ralph Waldo Emerson

[bhupender rawat]

Thanks for the quick response. What is the common practice for local conference with thin same cluster locally. Is that the CUCM based software conference should be used.

One scenario- > i am on conference between three local parties (I would say CUCM software conference used) , now i wanted to involve 2 branch phone which are on G.729 (as per region) how the transcoder will be involved.

Sorry for any confusing statement.

Thanks again. Appreciate your help.

[Ayodeji Okanlawon]

The best practice is to use hardware conference bridge especially in your scenarion where you have branch phones configured for g729. You also need to ensure that you have seperate MRG for hardware conference bridge and software conference bridge. The software conference bridge is created automatically.  So I will suggest that you put your software cfb into a software_MRG and your hardware into a Hardware_MRG and then assign them to a MRGL

In the scenario you described the g729 phones will not be able to join the conference natively,hence a xcoder will need to be invoked for them to join the conference. This is why in a scenario like this it is better to use hardware conference bridge so you dont involve a xcoder.

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"'Nature is too thin a screen, the glory of the omnipresent God bursts through it everywhere"-Ralph Waldo Emerson