Voice quality

[PeterCheng]

Hello sir,
our environment:
1. on-premise linuxed-based 3CX server (vmware environment) placed in our DMZ zone.
2. version is 18.0.237
Recently more and more employees complaint that no matter where they are (in the office or at home), or what they use (laptop app or mobile phone),
and what numbers they call (internal call or external call), they sometimes encounter bad voice quality.
It could be crackle / metallic voice. After I myself did the several tests and I also could hear such kind of issue with voice.
When using Windows desktop app to make a call, sometimes it will show "disconnected, waiting for netwok", but in the meanwhile, we can ping the 3CX server smoothly and response quickly.
So it's impossible that it's network issue.
When using mobile phone app (android phone) with 4G, I will also encounter similiar situation. when calling out, I can sometimes see the signal indicator from green to original to red , even disappeared, but I can ping 3CX normally.

Because poor quality is not always happen, but I think it's not hard to simulate the condition.
Could everyone give me some recommendation to solve this problem?
How to clarify the root cause? Thanks.

Peter

 

[cobaltit]

The fact that you don't drop pings does not mean it's impossible that it's a network issue. Ping is the most rudimentary of troubleshooting tools to help identify obvious network issues.

Call quality issues are most commonly network related, be it local network or on your dial tone provider's network. But it can also be resource related (not enough CPU cycles), but if that's the case, that would typically be due to transcoding. Since this is VMware can you add more CPU cores to the VM? Is there a firewall between 3CX and your internal network since it's in a DMZ? Can you put some devices in the DMZ to rule out the firewall?

- First you want to identify when the issue started. Did it happen since day 1? Did it happen after upgrading to v16? Once you identify when it started, you can look for possibly related changes. Everyone always said nothing changed, but I've yet to see something break when nothing changed.
- Since this is an audio issue, you want to eliminate as many legs in the audio path as possible. Start with a single device using echo test. Can you recreate the problem via echo test? What about between two brand new extensions, making sure the PCMU or PCMA (depending on your country) is the top codec on both extensions and using a 3CX softphone or web client on both ends. Then you can start expanding including other devices, other locations (cell phone outside the network),

Check those things first and you'll probably find the issue.

 

[PeterCheng]

@cobaltit ,
We didn't change any environment for network or security setting.
And we doubted that it's caused by 3CX server itself.
In the past we installed 3CX with Debian version 16, and then we upgraded it to V18 first,
and later we continued to upgrade to update 1 final.
And I don't know when, but more and more people complaint about the voice quality.
And I myself also encounter the same issue.
We had ever adjusted codec but no use, after all, we decided to reinstall a whole new 3CX server.
Right now we are using the latesting 3CX ISO file and today I felt the voice quality gets a great improvement.
I just shared my experence to people who encountered such issue can give it a try.
Thanks.

Peter

 

[NickD_3CX]

Hi Peter,

I'm glad to hear that after re-installing things seem to be better.
In Virtual Environments, make sure that you don't over-allocate resources as that can be tricky to detect.
Also, inside the VM, make sure you install the Hypervisors agent, in the case of VMware, I believe it is VMWare Tools.

We advise this also in out guide:
https://www.3cx.com/docs/manual/installing-debian-linux-pbx/#h.5hoy5wwhhk5c

I believe this is what you are looking for by the way.