[WXC/VFX] VoIP Call Quality

Forums › One New Zealand (including Vodafone, WxC, Farmside) › [WXC/VFX] VoIP Call Quality

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#80015 27-Jul-2007 16:37

I dont think the ISP would be the cause of quality issues on G729 seeing as it requires alot less bandwidth. Maybe its the phone (Linksys SPA942).

Even while a call is ringing (Out) it sounds terrible. I'll try doing some recording over the weekend to demonstrate the quality differences.

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grant_k

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#80019 27-Jul-2007 16:51

If you have significant packet loss or jitter -- which causes packets to arrive out of sequence -- you will get severe degradation of audio, no matter which codec is in use. Yes, the bandwidth is much lower on G729 but it still needs stable latency i.e. low jitter, or the order of the packets gets mixed up. It also needs minimal packet loss.

Woosh's Orbit Flat Rate plan (along with most other plans of this type) is notorious for both of those issues due to the traffic shaping devices employed. A mate called me using Skype via Woosh Flat Rate a couple of months back. The quality was awful, so I know the problems with VoIP and Woosh Flat Rate plans from personal experience.

ajobbins

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#80029 27-Jul-2007 17:02

We were formerly on the flat rate plan but changed due to the crapness of it, but it's really no better now.

Sound quality of 711u is great, really great (ISDN like), but you miss every 15th or so word (I assume a bandwidth issue), 729 sounds like GSM in a tunnel.

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maverick

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WorldxChange

#80030 27-Jul-2007 17:07

Hi Adam,

Grant is quite correct and I'm afraid we have seen poor performance on the Woosh network for real time apps we have had a few people try it on Woosh with pretty poor results, we also tried it ourselves and were not impressed, if you get a chance try plugging your device into another network connection , maybe a friends place or at work

, compare the difference then I think you will be surprised in the quality difference on better preforming networks.

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

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Niel

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#80059 27-Jul-2007 20:56

Friday Winter's evening 8:45, and I'm getting 6.5Mbps. I'm with XNet. Always had low pings (below 50ms to their server) and good bandwidth. And my VFX has always been perfect.

As Phil (Maverick) suggested, try plugging into another network. All networks are not equal. I also had it on my father-in-law's slow rural ADSL line (with Xtra), and the quality was still good even though the ping was a lot longer.

You can never have enough Volvos!

ajobbins

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#80150 28-Jul-2007 19:23

This morning I turned on the 'Reserve bandwidth for VoIP calls' and plugged the phone into the DSL modem/router (RT1320) instead of the D-Link router I was using. Instant improvement. Some more tests to be done but I am very happy with results thus far.

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grant_k

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#80151 28-Jul-2007 19:36

adamj: This morning I turned on the 'Reserve bandwidth for VoIP calls' and plugged the phone into the DSL modem/router (RT1320) instead of the D-Link router I was using.

Aha!!! Now I think I see what was happening...

How have you had these two devices interconnected until now?

Something like this maybe?

ADSL Line --> RT1320 (LAN port) --> (WAN port) D-LINK Router (LAN port) --> SPA942

If that's the way you had it connected, this would mean that you had 2 NAT devices between the SPA942 and the internet. And 2 lots of NAT is not recommended for VoIP.

Whereas now presumably, your setup looks like this:

ADSL Line --> RT1320 (LAN port 1) --> (WAN port) D-LINK Router (LAN port) --> Other PCs
(LAN port 2) --> SPA942

Meaning that you have only one NAT device between your SPA942 and the internet.

Have I got the right idea here?

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Niel

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#80154 28-Jul-2007 19:58

The RTA1320 has only on LAN port, the SPA942 has 2 Ethernet ports and is now connected in series between the modem and the router. That is your best option.

You can never have enough Volvos!

ajobbins

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#80155 28-Jul-2007 20:34

Original Setup:

DSL Line-----> RTA1320 (IP Extn on)-------------->D-Link DI704-UP----------->Several clients including SPA942

Now:

DSL Line-----> RTA1320 (IP Extn off)-------------->Switch------->D-Link DI704-UP----------->Several clients EXCLUDING SPA942
-------->SPA942

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grant_k

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#80158 28-Jul-2007 21:39

Adamj: A couple of questions if you would be so kind:

1) What does IP Extn On or Off on the RTA1320 do? Does it turn NAT on or off?

2) I suspect that the improvement in your call quality is because of the change in connection of the SPA942 rather than the 'Reserve bandwidth for VoIP calls' function of the RTA1320.

Would you be able to turn that function off and see if the call quality is still OK or whether it reverts to the poor quality previously experienced?

This would be an interesting experiment which will hopefully prove the point one way or the other.

Cheers,
Grant.

ajobbins

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#80172 29-Jul-2007 09:24

IP Extn turns NAT off and assigns the WAN IP address to whatever is plugged into the LAN port on the RTA1320

With IP extn off and the SPA942 plugged in via the DI-704UP (So double NAT) the quality was the same as with IP extn on.

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grant_k

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#80173 29-Jul-2007 09:29

adamj: IP Extn turns NAT off and assigns the WAN IP address to whatever is plugged into the LAN port on the RTA1320

Interesting... Because you have 2 devices plugged into the LAN port of your RTA1320 by virtue of the switch:

1) D-Link DI704-UP
2) SPA942

I wonder which of these is getting assigned the WAN IP address?

grant_k

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#80175 29-Jul-2007 09:32

adamj: With IP extn off and the SPA942 plugged in via the DI-704UP (So double NAT) the quality was the same as with IP extn on.

Great! Thanks for testing this Adamj.

So... Let me make sure I have got this straight now:

You are saying that whenever the SPA942 is plugged in via the DI-704UP, the Voice Quality is bad regardless of whether IP extn is ON or OFF?

ajobbins

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#80179 29-Jul-2007 10:36

I'll have a play with the SPA plugged into the switch with VoIP prioritisation off and see if that makes much difference. I'm at work at the moment so cant try it out.

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ajobbins

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#80180 29-Jul-2007 10:37

Grant17:
adamj: With IP extn off and the SPA942 plugged in via the DI-704UP (So double NAT) the quality was the same as with IP extn on.

Great! Thanks for testing this Adamj.

So... Let me make sure I have got this straight now:

You are saying that whenever the SPA942 is plugged in via the DI-704UP, the Voice Quality is bad regardless of whether IP extn is ON or OFF?

Exactly

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