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?

 

[chance-wmt]

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

Yes, however only the trunk needs to change the codec, the server will convert this for you. You do not need to change any codecs except your truck and on your carrier.

 

[amir_]

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

After 15 years of Cisco IPT engineering, it sure is nice to have this forum and real world responses like this.

So we are definitely behind a Ribbon SBC. I noticed the following are slightly different and I assume these are defaults because I didn't change them. Also, our Ribbon SBC -- 3CX trunk is configured for PBX Delivers Audio.

Settings>General>Codec Priority for Local/Internal Calls

PCMU

PCMA

G722

GSM

G729

OPUS

Settings>General>Codec Priority for External Calls

PCMU

PCMA

GSM

G729

G722

OPUS

 

[chance-wmt]

Those are for if you create new extensions or Trunks. Since you already created these, modify your Codec under your SIP Trunk.

 

[amir_]

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

@chance-wmt - Could I clarify my understanding of the codec order and location please:

1. Location - on Ribbon SBC - 3CX Trunk > Options > Codec Priority

2. Order - G722, ULaw, ALaw, G729

And lastly, do you use Flowroute or Telnyx?

 

[chance-wmt]

We use Telnyx but not Ribbon SBC (SBC SWe)

 

[chance-wmt]

@amir_ I am intrigued with Ribbon SBC, we are looking into working with Bandwidth but they want to whitelist IPs. We are looking into Ribbon to resolve this inconvenience. Could you follow me to allow private conversations? I have a few questions and I could answer yours.

 

[amir_]

@amir_ I am intrigued with Ribbon SBC, we are looking into working with Bandwidth but they want to whitelist IPs. We are looking into Ribbon to resolve this inconvenience. Could you follow me to allow private conversations? I have a few questions and I could answer yours.

I have a GREAT CCIE who left Cisco for Zoom a year back. Deji is truly the best and he recommended Ribbon and deployed the 2900E for us. Apparently, that is one of the Zoom Phone SBCs that he commonly deploys. It is working great so far.

 

[ChrisC_3CX]

Settings>General>Codec Priority for Local/Internal Calls

PCMU

PCMA

G722

GSM

G729

OPUS

Settings>General>Codec Priority for External Calls

PCMU

PCMA

GSM

G729

G722

OPUS

Regarding the codec settings under "Settings >> General", I just want to clarify that they are not the default codecs set for newly created SIP Trunks or Extensions. These are the codecs used by the 3CX PBX in the SDP. That said, if you wish to reduce transcoding to a minimum, you will need to modify the codec order here as well, for both remote/external and local/internal calls.

So you would have to try and keep the same order in:

1. Settings >> General >> Codec Priority: Both external and internal.
2. Extensions >> Edit >> Phone Provisioning: Select the 3CX App for 3CX clients or the specific IP Phone if a deskphone is being used(deskphones will need to be reprovisioned to apply changes).
3. SIP Trunks >> Edit >> Options.

Note: You might also want to check with your provider for their codec priority in order to match yours with theirs.

Also bear in mind that 3CX v18 has been designed to help keep transcoding to a minimum so you can either follow the above guidelines temporarily until v18 comes out or just wait for the official release if this is not a major issue.

 

[luckystrikes]

Hi,

Have you seen this thread - https://www.3cx.com/community/threads/inbound-call-audio-flowroute-gc-vm.81345/#post-375749

I am having the same issue, I've also opened tickets with FR. Have not yet with GCP but that Telynx was able to disable a PSTN route and fix it makes me want to switch to Telynx even more.

 

[chance-wmt]

Hi,

Have you seen this thread - https://www.3cx.com/community/threads/inbound-call-audio-flowroute-gc-vm.81345/#post-375749

I am having the same issue, I've also opened tickets with FR. Have not yet with GCP but that Telynx was able to disable a PSTN route and fix it makes me want to switch to Telynx even more.

We had the same issues with Telnyx... We had to finally submit our own recording. We found their secret NOC Priority line lol

 

[easttek]

Had a response from flowroute today, they are taking all of my DIDs that are on Google Cloud PBXs and moving them to a different carrier/peer. I'm skeptical about the results but they did admit they've had many tickets open recently regarding this carrier in particular and the carrier in question was not particularly helpful in trying to resolve issues. Will update when switch is made.

Also, they traced some calls and showed me some odd data along the line, incoming calls hitting multiple PBXs and SBCs of mine before hitting the right destination. That's while using their integrated Hostname registration. Almost as if registration to flowroute isn't working as it should. Very confusing.