Transcoder Usage Question

Answered Question
Oct 4th, 2008

I have two sites we'll call A and B seperated by a WAN. I have my regions set up on CUCM such that phones in site A always use G.729 to call phones in site B and vice versa.

The CUCM server is in site A and for a few months at least the Unity server will be at site B. Unity only talks G.711. Therefore I need a transcoder to convert the G.729 stream from phones in site A to G.711 for Unity in Site B but I want this transcoding to happen AFTER (not BEFORE) crossing the WAN link.

Here's the issue... I have 2811 at each site with Transcoder configured. Seems to me though that since my Media Resource Group for Site A is configured to use the Site A transcoder then I will be converting the G.729 to G.711 BEFORE I cross the wan. As mentioned I want to have the transcoding done at the far end at site B so that I'm just sending G.729 over wan.

In configuring Media Resource Groups in the scenario would it be normal to put the opposite sites Transcoder in the MRG intended for the local site or am I missing something else here?

TIA!

I have this problem too.
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Correct Answer by gogasca about 8 years 2 months ago

Hi flash2200:

Let me clarify whats CallManager logic in this particular scenario:

Lets say: Party A and Party B, the inter-region BW between A and B is: regionABbw, and there is no matching cap between A and after region filtering.

CUCM will behaves as following:

Party A: IP Phones

Party B: Unity

regionABbw: G729

If A has codec whose BW is less or equal to regionABbw, but B does not. Then one transcoder will be needed, and will be allocated on B side. So is vice versa.

So in this case configure under Unity VM ports an MRGL that have access to the XCODER u want to use before WAN.

HTH

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a.gooding Sat, 10/04/2008 - 20:37

if im not mistaken unity talks both G711 and G729 (were not speaking unity express right?). other than that what ive done in the past is this. for the new unity that uses voice recognition software we must use G711 but obvoiusly we still want to pass G729 across the WAN. therefore, ive put UNITY in its own region/Device pool. i then associate accordingly like below

CALLS from SITE A TO B (vise versa) - G729

CALLS from SITE A to UNITY -G711

CALLS from SITE B to UNITY - G711

are we on the right track here or have i misinterpreted the question

Marwan ALshawi Sat, 10/04/2008 - 20:49

hi ARVIND

in ur case that means u have created separate device pool for UNITY (which include the region as UNITY)and then u applied this device pool to the voice mail ports ??

thanks

Marwan ALshawi Sat, 10/04/2008 - 20:37

ok the thing is

as long as the call between regions is set to g729 the call when traverse the WAN between regions will be converted to g729 because cisco ip phone has guiltin dsp that able to Xcode diffrent codecs the operation between ip phones is simple and dose not need transcoder but when u caome to case like urs now the voice mail use only g711 in the case the call wil traverse the WAN if the call considered between to regions as u set it will be g729 when the call will go on the remote site to the voice mail the transcoder will be invocked at that stage

and the transcoding resources will be used based on the MGRL configured and will be used in the oreder configred in the MGRL/MRG

in ur case if the site A Xcoding listed first that mean this call will use site A transcoding rsources first if there is no enough transcoding on the site A will go to the next listed on which is Site B

in other words the order in the MRG relate to which resources this device will use and the region will be resposible for type of codec

by the way the same idea is when u use g729 between sites and u wanna use the remote site PSTN !

good luck

if helpful Rate

Correct Answer
gogasca Sat, 10/04/2008 - 20:59

Hi flash2200:

Let me clarify whats CallManager logic in this particular scenario:

Lets say: Party A and Party B, the inter-region BW between A and B is: regionABbw, and there is no matching cap between A and after region filtering.

CUCM will behaves as following:

Party A: IP Phones

Party B: Unity

regionABbw: G729

If A has codec whose BW is less or equal to regionABbw, but B does not. Then one transcoder will be needed, and will be allocated on B side. So is vice versa.

So in this case configure under Unity VM ports an MRGL that have access to the XCODER u want to use before WAN.

HTH

Marwan ALshawi Sun, 10/05/2008 - 00:52

hi GONZALO

i think ur answer agree with mine .. i think this is the best way to be achieved through

iptuser55 Thu, 10/09/2008 - 04:53

Sorry to jump into this conversation but I also have a similar set tup

Site A has a central Unity Connection and Site B.....Z are remote sites

Calls internally in Site A are G711

Calls to between other Sites are all G729

Unity is currently set to use G711

Site A user dial Unity as G711- No transcoding

Site B User dials Site A user devices use G729 as part of their handset- no external transcoding done via the handset

Site B user dials Unity at Site A

First part of call across the WAN uses G729 to enter Site A

Next Stage of call now needs to be xcoded to G711 so Unity can "understand" it

Just to confirm - Do I set up the Voice Mail ports so to use their own MGL and transcoders at Site A since the call is coming to them already as G729 due to the "forced" location/ regions setting they have to use for Inter Site calls and the Voice Mail Ports have to xcode G729 back G711 ?

thanks

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