Codec

Unanswered Question
Apr 7th, 2007

Can someone explain the difference between 729 and 711 codec, and the advantages and disadvantages?

I have this problem too.
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thisisshanky Sun, 04/08/2007 - 10:01

Codec is a short term for Coder/Decoder.(Coding/Decoding). Its nothing but conversion of analog to digital and vice versa. There are different algorithms available to do this conversion and some are very simple while some are complex. Based on the same above reason, you may find a low complexity or high complexity codec. Codecs also compress the data (voice information) to save bandwidth. G711 is one of the most commonly used codec. The advantage of using g711 is the call quality is good. It uses 64 kbps per call (in theory) and uses PCM to encode voice.

G729 is a more complex codec and it uses CS-ACELP algorithm and uses some prediction tables to encode/decode voice. The advantage of using g729 is that you save on bandwidth. In theory, g729 consumes only 8kbps of bandwidth. Human ear is not so sensitive to clearly distinguish the quality of audio of a g729 versus g711 call. So if using g729 you will consume less bandwidth per call at the cost of some degradation in voice quality, not so noticable by human ear. Cisco IP Phones are capable of supporting both codecs. The best practice is to use g711 when there is plenty of bandwidth available, and use g729 when bandwidth is limited. So in the LAN, you should use g711 and across a wan when bandwidth is limited use g729.

You can see the various codecs available as well as the algorithms used by them, the bandwidth, bitrate etc in this link.

http://www.en.voipforo.com/codec/codecs.php

HTH

Sankar

PS; please remember to rate posts

omgjames1 Mon, 04/09/2007 - 09:45

If we switched to g729, will we be able to listen to voice mails through unified messaging?

Example.....

right now my voice mail goes to my outlook account, and my Treo 700w is connected to my outlook account, would i be able to play the message on my Windows Mobile phone without the use of a 3rd party app?

wahab101 Mon, 04/09/2007 - 19:15

As Sankar indicated it depends on THE BANDWIDTH

Make sure to use g711 within your office for the IP phones and g729 with another office .

You will get voice mail when you use the g729 for example your remote site phones will get their voice mail from the headquarter unity when they have a message.

rhugo Sun, 06/24/2007 - 06:10

We are dealing with this same thing. We already use the mVoiceMail from motionapps for playback, but is there some type of 3rd-party app that gives the full services equivalent to, say, Unity Inbox or ViewMail does?

Thanks!

nagabhushanamj@... Mon, 06/25/2007 - 04:17

Hi,

In the topic of Codec, I have 1 query.

Whether can we use G.729 on 64Kbps leased line.

Network: CCM4.2 at central location with 3- 7906G ip phones, 1 Ip Phone at 5 diff remote locations, connected through 64Kbps Leased line. Now we have enabled G.729.

Can we do the con call on this setup.

What is the best codec for con call.

Regards

Naga.

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