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G.729 vs G.711

<br>We are installing Unity 3.0x for use in our LAN, but we are probably going to install Call Manager for our remote offices.<br><br>I remember stumbling across a potential issue somewhere in your documentation (sorry I can not be more specific) which mentioned a possible conflict when running both G.711 and G.729.<br><br>Would it be better to stick with pure G.729? How much does it reduce the message size? And how bad exactly is the degradation when you say "The sound quality of G.729a recorded messages may be slightly decreased compared to the quality of G.711 recorded messages"?<br><br>thanks<br>m<br><br>

6 REPLIES
Anonymous
N/A

Re: G.729 vs G.711

Use G.729 if the calls terminating on Unity will be traversing the WAN. G.729 uses 8kpbs per call, though the actual bandwidth used can effectively be as much as 20kbps and theoretically as high as 35kbps. I've never seen anything higher than 20kbps per call. I plan on 12kbps per call and then measure call bandwidth and adjust the WAN link accordingly.

Use G.711 if all calls terminating on Unity only traverse the LAN. G.711 uses 64kbps per call, and it can theoretically be higher than that, though I don't bother myself with the bandwidth since the only potential bottlenecks are badly configured switches.

Yes, G.711 sounds better than G.729, but I know the Mean Opinion Score (a measurement of how good people think calls sound) for G.729 isn't shabby at all (around 3.5??). It is on par with a decent cell phone call.

Related to this is codecs for other voice apps. Unity is the only voice app by Cisco that supports G.729, to my knowledge. If you are using any other voice apps whose calls terminate on devices across the WAN, you'll need to get a DSP farm that translates those codecs for you. DSP farms fit into network modules in routers and gateways such as the VG200. And they cost a lot, but less than the price of a bigger pipe.

Brandon

Brandon

Anonymous
N/A

Re: G.729 vs G.711


Can we switch from G.711 to G.729 easily later, if we decide to implement G.711 intially?

thanks
m

Anonymous
N/A

Re: G.729 vs G.711

I've never upgraded to G.729 before. You might have to reinstall the AV-TSPs, but that is only a guess. Here is the procedure to install G.729 when you are installing the server for the first time. Try installing as G.711, and then upgrade to G.729. and test it.

What I want to know is this. Is there a way to move from G.729 to G.711?


Step 1 Stop Cisco Unity (on the Cisco Unity server right-click the Cisco Unity icon in the system tray, then click Stop Unity).

Step 2 Browse to the CommServer\Utilities directory.

Step 3 Double-click the Sl_g729a_setup.exe file.

Step 4 Follow the on-screen instructions.

Step 5 When prompted, restart Windows.



Gold

Re: G.729 vs G.711

You don't need to reinstall the TSP. All the Sl_g729a_setup.exe file adds is the codec for Windows and turns g.729 support on in the registry.

Keith

Keith Chambers
Unity Technical Lead
Unified Voice Team, San Jose
Cisco Systems
kechambe@cisco.com

Anonymous
N/A

Re: G.729 vs G.711

What key in the registry do you use to turn G.729 off and use G711? Is there a utility to do it?

Gold

Re: G.729 vs G.711

The key is:
HKEY_LOCAL_MACHINE\SOFTWARE\Active Voice\AvSkinny
"G729 Enabled"=dword:00000001

You can use this tool to turn it on:
http://www.answermonkey.net/App_RegistryEdit.htm

Keith

Keith Chambers
Unity Technical Lead
Unified Voice Team, San Jose
Cisco Systems
kechambe@cisco.com

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