Unity Connection2.x - codec transcoding

Answered Question
Aug 2nd, 2008

-Unity Connection 2.x

-general configuraion recording format=g711

-port group codec advertizing codec=g711 and g729

My understanding is all g711 format base on the above environment for call handler greeting and user voice mail box

Q) when I access the CUC from remote IP Phone which is coming with g729 codec, how the transcoding happen?

-trasconding by CUC which is same way to Unity server software transcoding?

-if yes, what's CUC built-in transcoding capacity? (Unity server has very limited capacity so I want to know how works in Unity Connection)

-what is best practice the transcoding? do I need extenal transcoder which is same way to Unity server? (*1)

(*1) my case, not used the external transcoder when advertizing codec=g711 & g729. the external transcoder used when the CUC advertizing codec=g711 only. looks transcoding always by CUC when the advertizing codec=g711 & g729 both.

-->if CUC has built-in transcoding capacity limitatation (compare to Unity server), do I need change to g711 only in CUC and external transcoder for best practice?

Thanks in advance,

I have this problem too.
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Correct Answer by thfergus about 8 years 5 months ago

The recording format under the General Configuration settings determines the audio format for all messages, greetings, and names system-wide for all users.

When you connect to the Unity Connection server with an ip phone using the G729A codec and the recording format is set to G711 u-law or a-law, the Unity Connection server performs transcoding on-the-fly in software; no DSPs are used. This can impact performance on the Unity Connection server.

If two or more codecs are in the Advertised Codecs box, Connection will advertise its preference for the first codec in the list but will send the media stream in the audio format from the list that the callmanager selects.

Depending on the number of users connecting to the Unity Connection server using the G729A codec and the platform overlay used, it may be best to use external hardware DSPs

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Correct Answer
thfergus Sat, 08/02/2008 - 18:29

The recording format under the General Configuration settings determines the audio format for all messages, greetings, and names system-wide for all users.

When you connect to the Unity Connection server with an ip phone using the G729A codec and the recording format is set to G711 u-law or a-law, the Unity Connection server performs transcoding on-the-fly in software; no DSPs are used. This can impact performance on the Unity Connection server.

If two or more codecs are in the Advertised Codecs box, Connection will advertise its preference for the first codec in the list but will send the media stream in the audio format from the list that the callmanager selects.

Depending on the number of users connecting to the Unity Connection server using the G729A codec and the platform overlay used, it may be best to use external hardware DSPs

cjrchoi11 Sat, 08/02/2008 - 19:17

Thanks your reply,

Is there any CUC built-in transcoder capacity information? for example, max transcoder sessoin per platform overlay.

I'm planning 100 IP phones (among 2,000 IP Phones total) coming with g729 which is expecting 10*g729 concurrent calls (10% concurrent call assumption) and need to assess the best practice.

-if CUC fully supports the built-in transcoder to meet my requirement, I don't need the external transcoder and nothing to be configured

-if extenal transcoder is always best practice regardless number of transcoder session, I need setup extenal transcoder

Advise please,

Thanks, John

DJ McCool Mon, 11/03/2008 - 06:16

Hey John, did you get to the bottom of this? I cannot find any recommendations on this anywhere.

Thanks,

Danny

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