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"Ray Burkholder" <ray@oneunified.net> Sent by: owner-nanog@merit.edu 02/10/2003 02:21 PM

To:        "Charles  Youse" <cyouse@register.com>, "Alec H. Peterson" <ahp@hilander.com>         cc:        <nanog@nanog.org>         Subject:        RE: VoIP QOS best practices

G.711 gives you the 64kbps quality you get on a channel in a PRI line.
No compression is performed.

G.729 is a well accepted codec that performs compression, and with ip
packet overhead, uses about 16 to 24 kbps (can't remember which).  It
gives voice quality very close to G.711.

G.723 has a noticeable voice quality change, and is in the 6 to 8 kbps
range.

The optimal is G.729 for quality vs bandwidth issues.

There are some other considerations involved but these are the main
ones.

Ray Burkholder


> -----Original Message-----
> From: Charles Youse [mailto:cyouse@register.com]
> Sent: February 10, 2003 14:42
> To: Alec H. Peterson
> Cc: nanog@nanog.org
> Subject: RE: VoIP QOS best practices
>
>
>
> Speaking of codecs, what are the primary variables one uses
> when choosing a codec?  I imagine this is some function of
> how much bandwidth you want to use versus how much CPU to
> encode the voice stream.
>
> C.
>
> -----Original Message-----
> From: Alec H. Peterson [mailto:ahp@hilander.com]
> Sent: Monday, February 10, 2003 1:40 PM
> To: Bill Woodcock; Charles Youse
> Cc: nanog@nanog.org
> Subject: RE: VoIP QOS best practices
>
>
> --On Monday, February 10, 2003 10:19 -0800 Bill Woodcock
> <woody@pch.net>
> wrote:
>
> >
> > It works fine on 64k connections, okay on many 9600bps
> connections.  T1 is
> > way more than is necessary.
>
> I'd say that largely depends on which codec you are using and
> how many
> simultaneous calls you will have going.
>
> Alec
>
> --
> Alec H. Peterson -- ahp@hilander.com
> Chief Technology Officer
> Catbird Networks, http://www.catbird.com
>