NO JOY call quality issues: delay and cut-outs (jitter?)

Rick Byrne

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Gentlefolk,

You all have been very kind by lending me a hand with getting my new 3CX system up and running. Forgive me if I seem to be requesting a lot of assistance. Perhaps someone else in the future will come across my threads and find an answer to their problem.

I'm having call quality issues when making calls over the PBX. The symptoms are popping sounds, delays, sometimes up to several seconds, and missed words or syllables.

The problems are more noticeable when calling outside my PBX, but the problems can also be heard when calling from one extension to another with "PBX delivers audio" enabled.

I deduce the problem lies with the PBX and not my LAN, firewall, or Internet connection. I will explain my reasoning using graphs from Wireshark.

Here's a traffic graph of a call to VoIP.ms' echo test line. Note the spikes on the forward difference and forward delta lines. I believe this is my problem.
34661329583_5d283e0ef1_b.jpg

https://www.flickr.com/gp/62754146@N08/N69y55

My PBX has two network cards in it: the on-board Realtek card and a PCI-E Intel card. The Intel card is the preferred network card, nevertheless, for the sake of troubleshooting, I ran traffic over the Realtek card, and had the same problems.
https://www.flickr.com/gp/62754146@N08/066EpG
35471012355_7b2569194c_b.jpg
N69y55


My first instinct is to blame my Internet connection or firewall. But there are even some spikes when dialing from one extension to another, with PBX delivers audio enabled:
https://www.flickr.com/gp/62754146@N08/V3w5e4

Ok, if there are quality issues calling between extensions, that means there's an issue with my LAN, right? When enabling sip re-invites, the phones can talk to each other independently of the PBX, and the quality is great. Note that the graph below is a different scale, because the values are so low!
https://www.flickr.com/gp/62754146@N08/x12vpw

When dialing via a sub-account, thereby bypassing the PBX entirely, the call quality is great. Note that are no spikes in difference / delta during the business of the conversation. So I deduce from this my Internet connection is good and my ISP isn't meddling with my traffic.
https://www.flickr.com/gp/62754146@N08/o6HBz6

I deduce, therefore, that there's a configuration or hardware issue with the PBX device itself.

I admit my hardware is not robust, but I think it's more than adequate for running 3CX. Here's my configuration:
https://www.flickr.com/gp/62754146@N08/2Ga369

What do you think?

Rick
 
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I doubt its a PBX software issue. If you are able to make good calls over that same network when not going through the PBX that then will potentially rule out the network. I assume you've run one of the internet tests for jitter and that in general your internet connection is good. There is either an issue with a hub or switch or the PC this is running on. Can you spin up something quick to test with on a different PC? Memory and resources are only one aspect. How the PC handles interrupts is another. I would remove the second card and anything else on the bus to test.
Also limit the codecs that are alloweded if you can.
 

Rick Byrne

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As always, Brian, you have excellent suggestions.

It does feel like a hardware issue, so I agree that testing with different hardware would be a good idea.

Disabling and removing unneeded devices is also a good idea.

I'll have to weigh the options I have and decide how to proceed.

I appreciate your input.
 
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Your welcome... Hope you nail it down soon. It may not seem so right now but all of this is excellent training!
 

Rick Byrne

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I post this update in case it is of value to anyone having similar problems who finds this thread in the future.

I installed FreePBX on the same hardware on which I was trying to run 3CX. Under FreePBX I am not having any of the problems described in my initial message.

I do not mean to imply that one platform is better than the other. Perhaps there's an incompatibility somewhere between PIAF 5's Debian OS, 3CX, my host hardware, and my phones.

I installed FreePBX on a separate drive, so I can easily switch back to 3CX. Perhaps a future update will address my issues.

I suppose, in fairness to 3CX, I ought to install 3CX on different hardware, as Brian suggests. However, at the moment, the only other hardware I have to experiment with is 32-bit, and the PIAF 5 distribution is only 64-bit.
 

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