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5 posts

Wannabe Geek

Topic # 65847 7-Aug-2010 15:03
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Hi all

I am using a ATCOM 530P VOIP phone on Actrix CyberJet Full Speed ADSL connection.

I have a DDI in South Africa.

What is puzzling to me is that the incoming SIP call quality is so much better than the outgoing call quality.

Just to be clear. When someone in South Africa calls my DDI and it rings here in New Zealand, the call quality is very good.

If I return the call via my Service Provider, the call quality is Ok to bad.

I am using G729 with 30ms pay load. I have tried 20ms, makes very little difference.

I suspect that the Parameters used by my Provider when setting up the call are different, and thus the better quality, or the network traffic routing for a call from SA-NZ is different from NZ-SA.

I had to change setting in my Thompson router to allow port 5060 and insert port forwarding of 5060 to the VOIP phones static IP address.

Any insight anyone has to this problem would be greatly appreciated.


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  Reply # 364679 7-Aug-2010 15:21
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Pretty much as you are suggesting, you will be most probably have different carriers, it will most likely have nothing to do with your setup, I do recommend keeping it on 20ms FTP packet size though, your issue will be with the upstream providers toll provider, it would appear the people in SA are using a quality provider your Service provider may be using a lower cost service on your outbound, hence the difference in call quality between outbound and inbound.

If you have the abilty to get MOS stats from your device or VOIP provider that will also quickly tell you if you have any issue with this part of your connection, but I will lay money on the issue being my first suggestion.

Yes I am a employee of WxC (My Profile) ... but I do have my own opinions as well Wink


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  Reply # 364682 7-Aug-2010 15:25
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Do both inbound and outbound calls use the same codec?

THe G729 codec is a lower quality codec but is better at handling jitter and packet loss than G.711 ulaw or ulaw.

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