3CX or user error?

[BrandonMorkane]

We've setup a 3CX system using AWS and it has been working perfectly well for the last 6+ months. Recently, one user has noted frequent complaints from their customers regarding call quality. The user does not hear any crackling/distortion however the caller on the other end does.

This is only affecting one user in the office, all other users/extensions work perfectly fine.

We have not been able to replicate the issue on that users' phone/extension when testing, and the user assures us that they receive complaints from about 80% of callers each day. We have also created new extensions, changed handsets, used the web client, used the 3cx Mobile app but it hasn't fixed the issue.

Again, we have not been able to replicate the issue and no other users in the office are complaining about this.

Any help would be greatly appreciated!!

 

[leejor]

Being one user, it has to be the hardware (set), settings on the hardware (Codec?), a different route that calls are taking (does this affect internal calls too?), or the network between the set and the server. What hasn't been changed out?

 

[BrandonMorkane]

Only external calls are affected, internal calls are perfect. The previous staff member using the same hardware did not have this issue. It's only bee since the new person started that this has been made known to us.

The route that has been configured is used by all other extensions. I thought it might have been codec related too however the settings are an exact match for all other users in the office.

The only thing that we haven't changed out is the server where SBC is installed and the managed router (we have no access to the router onsite). We've swapped out the handset with a spare one, also swapped it with another users' handset, but it doesn't resolve the issue.

 

[JohnS_3CX]

Hi Brandon, what was your test methodology? That sounds like a strange case, I'm wondering if this happens when the user calls external numbers to a specific recipient provider.

If you do find a way to replicate it, try running a capture on the PBX and listening to the outgoing audio stream in WireShark to see if the audio leaving from the PBX IP and going to the Provider IP is degraded.

As this is an unusual case, ask the user to get some feedback from the other caller when switching to Speakerphone mode and back to handset (ensure no headset is used to minimize failure factors)

 

[BrandonMorkane]

Hi John, thanks for your message!. Here's what we've tried so far. (please let me know if I've missed something)

• We've checked Packet loss, High usage, Latency and any other Unusual activity, but it was all clear.
• We've also tested the following:
  • Multiple different handsets (they use Yealink W52H and T48S devices)
  • Created a new extension to test with
  • Swapped handsets from other users in the office
  • Change the base unit that the DECT handset connects to
  • Restarted the 3CX services and PBX Server

We haven't been able to replicate the issue and the wireshark scans we've run while the extension is on a call has not reported any problems.

My initial feeling was perhaps it was just the connection from the recipient, out of a dozen or so 3CX instances we've implemented, this site is the only one where we've installed an SBC tunnel, but again, it's been working perfectly fine up until this user started.

Definitely strange!

 

[JohnS_3CX]

I think an SBC issue would affect more than one user, so we can put that aside for now.

The DECT handsets (being wireless) could potentially introduce noise - but this would be heard in the call recordings or the wireshark audio stream playback for sure

As far as deskphones go, switching to speakerphone and asking otherside if the noise went away is a good way to troubleshoot both the handset of the device, and the spiral cord (often points of failure due to natural wear and tear). I test by replacing only the handset, and then the cord, and then to falsify my hypothesis I use the same cord and handset on a known-good deskphone, you'd be surprised sometimes

I think the strongest card to play would be a wireshark capture and hearing the stream that specifically goes from PBX->Provider to see if you are the one introducing the noise or it happens after the provider because you have also used web/mobile clients and still faced the issue.

 

[BrandonMorkane]

Thanks for that, I think I'll try a few different combinations just to be sure its not hardware related.

I'll get the user to switch to speakerphone and see if that makes a difference, and then run some wireshark scans to see if we can identify if there is an issue, and where its coming from.

Will keep you posted

 

[leejor]

Does the user, having the issue, recall if they were calling certain numbers? Perhaps certain mobiles (mobile provider), a certain company, Certain prefix, anything that might indicate a "pattern".

 

[BrandonMorkane]

I think an SBC issue would affect more than one user, so we can put that aside for now.

The DECT handsets (being wireless) could potentially introduce noise - but this would be heard in the call recordings or the wireshark audio stream playback for sure

As far as deskphones go, switching to speakerphone and asking otherside if the noise went away is a good way to troubleshoot both the handset of the device, and the spiral cord (often points of failure due to natural wear and tear). I test by replacing only the handset, and then the cord, and then to falsify my hypothesis I use the same cord and handset on a known-good deskphone, you'd be surprised sometimes

I think the strongest card to play would be a wireshark capture and hearing the stream that specifically goes from PBX->Provider to see if you are the one introducing the noise or it happens after the provider because you have also used web/mobile clients and still faced the issue.

Hi John,

So we have done some extensive testing, we've contacted confirmed numbers that have been causing the issues every single time for the user (yet we couldn't replicate the issue when calling them). While running wireshark, we found no errors when calling those numbers.

I took my Yealink T48S to their office to test with, since last Thursday, they haven't had any complaints. But what's more interesting is I took their unit back to my office to test, and it's been perfectly fine. No echo, no distortion or anything.

I also ran wireshark scans on their old device and our test device, no issues at all.

Overall, I'm happy this is no longer occurring but I'm baffled as to what the cause may be. Either way, the user is not complaining of the issue anymore so I will put it down to the unit and a combination of their network. Somewhat unsatisfying haha

I appreciate your time and help!

 

[BrandonMorkane]

Does the user, having the issue, recall if they were calling certain numbers? Perhaps certain mobiles (mobile provider), a certain company, Certain prefix, anything that might indicate a "pattern".

Hi Leejor,

Thanks for your comment, we tested confirmed numbers ourselves and had not been able to replicate or experience what the user claimed was bad crackling and distortion.

It's unusual because it affected only one user, changing extension didn't resolve it, changing devices didn't work the first time, it wasn't until we brought our device in that the user stopped complaining of the issue.

Most bizarre!

 

[JohnS_3CX]

Brandon, does this occur only on incoming calls or outgoing? I don't think we checked that part and it's important to try and replicate the original case conditions - outgoing calls can always be healthy since your provider will use their predefined healthy route BUT incoming calls are sent in from the caller's provider from any route they choose and sometimes noise may be introduced where you might not expect it (no matter how rare).

So IF it is only on incoming calls, the PBX-based capture between provider-and-PBX will prove whether the outgoing audio of your user is healthy AND at that point the issue goes out of your hands and into the hands of your provider since the noise must necessarily be produced anywhere downstream of your PBX.