Inbound Call Quality Issues

[Alec_SSIT]

We are experiencing inbound call quality issues on one of our Google Cloud Platform hosted clients. Other clients on the same configuration (including our internal setup) are not experiencing problems. When someone calls in, there is noticeable jitter on the line for our client's 3CX system. Outbound calls are perfectly clear, however. We use 3CX internally for our business as well as deploy this to clients. We have a known good 3CX setup on our network and things work properly there for our phone system. We setup a test extension for our client on our network and provisioned a phone to this extension. We are also hearing the same inbound call quality issues on the test extension on our network. This rules out their networking equipment and ISP. We do not expect there to be any bandwidth issues contributing to this as we have setup QOS and the used bandwidth when trouble is observed is very low (well under the maximum). We recently tried increasing CPU and RAM resources on Google Cloud, but issues persisted. Does anyone have any insight on what could be causing these call quality issues on inbound calls, or recommendations on next steps?

 

[easttek]

I am also having the exact same issue

 

[cobaltit]

Any chance you are using Flowroute?

 

[easttek]

Yes, sent pcap to flowroute and they said it was degradation on the Cloud server/PBX side. I plan on testing another provider tomorrow just in case. I'm experiencing the same issues on 2 out of 6 Google Cloud instances so it's certainly odd that flowroute + Cloud VM aren't causing an issue on the other systems.

 

[ChrisC_3CX]

@Alec_SSIT

First off, please provide all relevant information mentioned here: https://www.3cx.com/community/threads/information-to-provide-when-requesting-help.67558/

Also, the issue you mention for inbound calls, does it affect audio in both directions, both the audio received by the callee (3CX user) and the audio received by the caller (external caller)?

@easttek

Are all 6 instances you mention using the same provider?

 

[easttek]

Yes, same provider. Same size machines, all small offices. Tried increasing resources on the VM of the affected systems with no change. Also, in my case the broken stream is from caller to callee, the other way around is clear audio.

 

[ChrisC_3CX]

@easttek
In that case you might have to investigate a bit further.
I see you have submitted a new thread regarding this issue in the SIP Trunks section, I recommend proceeding with what my colleague suggested.

 

[Alec_SSIT]

@cobaltit --yes we are using Flowroute.

@easttek - Interested to hear what you find in testing another provider. Please let us know what you find! I have a support ticket open with 3CX on this so will post our findings, as well.

@ChrisC_3CX

• 3CX Version: Standard Annual 16.0.8.9
• Server OS, Debian 9
• Is the 3CX Server Hosted and where - Google Cloud Platform Hosted
• IP Phone Make/Model/Firmware Yealink SIP-T27G and Yealink SIP-T42G
• Provisioning Method: STUN
• Trunk Provider or Gateway Make/Model - Flowroute
• Has the Firewall Checker passed: YES
• Are custom Phone Templates being used: No

Only the 3CX call receiver (callee) hears static on the line. The call quality sounds fine to the the person calling in (caller).

We collected a Wireshark capture of the issue from our customer's network and the poor call quality/jitter on the internal call receiver is apparent on this capture, while the audio the caller hears is perfectly fine. The callee can end the call, call the original caller back, and quality is fine on both directions.

 

[ChrisC_3CX]

Hey @Alec_SSIT

Since you submitted a Support case with us, I recommend you continue investigating this issue with the help of our support team. I'll leave this thread open for now in case you want to post updates on the matter.

 

[chance-wmt]

Telnyx had the same issue, on our account on the backend they temporarily disabled inbound routing from one of their carriers on the PSTN because of these issues and it worked. This was fairly recent.

 

[easttek]

Update: Have not been able to deploy another provider as Im stuck out in the field but have seen improvements today by setting the lower bitrate G729 as the primary codec.

 

[chance-wmt]

Update: Have not been able to deploy another provider as Im stuck out in the field but have seen improvements today by setting the lower bitrate G729 as the primary codec.

G729 can be CPU intensive, we use G722, Ulaw Alaw G729 in this order

 

[easttek]

Yeah I'm aware, I'm strictly referring to alleviating the problem until this issue can be resolved. Flowroute supports G711U G711A and G729 the audio issues were experiencing seem to be alleviated slightly when using G729 for whatever reason.

 

[colonial]

Yes, sent pcap to flowroute and they said it was degradation on the Cloud server/PBX side. I plan on testing another provider tomorrow just in case. I'm experiencing the same issues on 2 out of 6 Google Cloud instances so it's certainly odd that flowroute + Cloud VM aren't causing an issue on the other systems.

I think flowroute had some trouble over the last couple days... we were experiencing this also...

 

[amir_]

G729 can be CPU intensive, we use G722, Ulaw Alaw G729 in this order

Hi,

I'm new to 3CX. Where specifically are you setting this codec order?

TIA,

Amir

 

[chance-wmt]

Hi,

I'm new to 3CX. Where specifically are you setting this codec order?

TIA,

Amir

Codec Priority under Trunk Options

 

[amir_]

Codec Priority under Trunk Options

We have Flowroute >> Ribbon SBC >>> 3CX and our CODEC priorities on the SBC to 3CX trunk are set to the what appear to be the defaults ULAW, ALAW, G729.

Thanks!

 

[easttek]

We have Flowroute >> Ribbon SBC >>> 3CX and our CODEC priorities on the SBC to 3CX trunk are set to the what appear to be the defaults ULAW, ALAW, G729.

Thanks!

You also need to set it in each extensions phone provisioning tab (and reboot/reprovision) and in the Settings/General tab.

 

[chance-wmt]

You also need to set it in each extensions phone provisioning tab (and reboot/reprovision) and in the Settings/General tab.

This is incorrect unless you have PBX delivers audio disabled

 

[easttek]

This is incorrect unless you have PBX delivers audio disabled

He said he was behind SBC, typically you are not required to have PBX delivers audio enabled in that configuration