What G723 codec do you have on Asterisk? What is your SIP.CONF? What
ATA/Phone is being used and what are the exact settings, especially
for the codec?
On 1/19/07, Phil French <pfrench@caprock.com>
wrote:> I am setting up Asterisk for use in a low bandwidth environment. As
> bandwidth is precious and our ATA's support it, the decision was made
to
> use the g723 codec. I have been working on this for a few days and have
> not been successful. The issue that I am having is garbled noise at the
> client on calls whose RTP streams are terminated by Asterisk system.
> This is the case for all the dialplan applications I have tested except
> for Echo. The critical application for us is Voicemail. When a call to
> voicemail extension is initiated the Asterisk console does not indicate
> any error. Packet captures indicate the call is active and streaming
> g723 data. Everything seems well but is not. The audio at the client
> is unrecognizable. One thing that I have noticed is that the bitrates
> in the upstream and downstream direction differ. From Asterisk to ATA
> the g723 bitrate switches between 5.3 kb/s and 6.3 kb/s. From ATA to
> Asterisk the bitrate is a constant 6.3 kb/s. I don't think this is a
> problem but seems odd. As a comparison I captured packets from a call
> to the echo application and found that the bitrate was 6.3 kb/s in both
> upstream and downstream packets. Additionally, all prompts are g723
> format. Voicemail is saved as g723sf. As a parrallel task a co-worker
> has gotten 1.2 to work with g723. However we require 1.4 for t.38
> pass-through.
>
> The end-to-end system is illustrated below.
>
> [Asterisk]
> / \
> ip ip
> / \
> [PSTN]--pri--[GATEWAY]--ip--[ATA]<--2pr-->[Phone]
>
> System details
> -Asterisk server version 1.4 - compiled from source - Fedora Core 6
> -Gateway - Cisco 2811 -ATA - Linksys 2102
>
> I would appreciate any advice or suggestions. It should be noted that
> the calls to the PSTN through the gateway and calls between ATA's are
> working fine.
>
> Regards,
>
> Phil French
>
> Phil French
> Systems Engineer
> -------------------------------
> CapRock Communications
> 4400 S. Sam Houston Parkway E.
> Houston, Texas 77048
> Office: 832 668 2643
> pfrench@caprock.com
> www.caprock.com
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