Poor Sound Quality or No Sound On External Calls

[AlphetaCS]

I'm working to transition a client off of their existing system onto 3CX, but I'm running into sound issues. They started slow with just making external calls (nothing incoming) for about a week and it went well with the occasional complaint about sound quality. When I started forwarding all calls to the 3CX system there were a lot of issues with sound quality or no sound, but the server resources all looked great. The PBX is hosted in the cloud (Vultr) and I have an SBC on premise, but this client has a requirement to record all external calls and I've read that call recording will bypass the SBC and route all audio through the PBX. I'd like to keep the SBC local and the PBX in the cloud. There is a pfSense firewall on premise. Any advice for configuration adjustments? Should I be opening up ports in the firewall to accommodate the call recording need?

Here are the standard questions / answers:

• 3CX Version: Enterprise Annual 18.0 (Build 450)
• Server OS: Debian 10
• Is the 3CX Server Hosted and where? Hosted on Vultr / SBC on premise
• IP Phone Make/Model/Firmware version: Grandstream GXP2160 1.0.11.35
• Provisioning Method: SBC
• Trunk Provider or VoIP Gateway Make/Model: Voxtelesys
• Has the Firewall Checker passed: Yes
• Are custom Phone Templates being used: No

 

[leejor]

It may have something to do with the Codecs being used on external calls, and whether or not transcoding is taking place within 3CX because of the recording.
If you place/receive calls from an extension that does not record, are there the same issues?
Does the 3CX Activity log show transcoding taking place (verbose setting)?
What Codec is the trunk using?

 

[ChrisC_3CX]

Since this involves external calls, it means the SIP Provider is also in the mix, so to try and narrow this down first do consider the following:

• Who of the two call participants is experiencing bad audio(actually hears it)? The 3CX user, the external caller/callee, or both?

• Listen to the recording of an affected call, does the exact same apply? For instance if the user reported that he heard audio just fine but the external caller could not, does the same apply for the recording?

 

[AlphetaCS]

It may have something to do with the Codecs being used on external calls, and whether or not transcoding is taking place within 3CX because of the recording.
If you place/receive calls from an extension that does not record, are there the same issues?
Does the 3CX Activity log show transcoding taking place (verbose setting)?
What Codec is the trunk using?

The Codec Priority for the SIP trunk is G.711 U-law, G.711 A-law, G729

I'll turn on verbose and see if there are any entries that help shed light here.

 

[AlphetaCS]

Since this involves external calls, it means the SIP Provider is also in the mix, so to try and narrow this down first do consider the following:

• Who of the two call participants is experiencing bad audio(actually hears it)? The 3CX user, the external caller/callee, or both?

• Listen to the recording of an affected call, does the exact same apply? For instance if the user reported that he heard audio just fine but the external caller could not, does the same apply for the recording?

Neither party can hear each other. In the case when neither party could hear each other the 3CX user is heard on the recording but not the other party. After listening to around 10 recordings, I don't hear anyone complain about the sound quality (although there are a lot of recordings to go through).

 

[ChrisC_3CX]

Neither party can hear each other. In the case when neither party could hear each other the 3CX user is heard on the recording but not the other party.

If neither part can hear each other, but you can hear the 3CX user on the recording file then you know that:

1. The audio from the 3CX client up to the PBX is fine.
2. Audio from the external party is never received by the 3CX PBX.
3. Audio from the 3CX PBX never reaches the external party.

With the above info you can deduct that the issue is outside of 3CX and specifically, probably between the PBX and the SIP Provider. If everything is ok with the PBX's network and firewall configuration then the next thing I would recommend you do is reach out to the SIP Provider.

 

[AlphetaCS]

If neither part can hear each other, but you can hear the 3CX user on the recording file then you know that:

1. The audio from the 3CX client up to the PBX is fine.
2. Audio from the external party is never received by the 3CX PBX.
3. Audio from the 3CX PBX never reaches the external party.

With the above info you can deduct that the issue is outside of 3CX and specifically, probably between the PBX and the SIP Provider. If everything is ok with the PBX's network and firewall configuration then the next thing I would recommend you do is reach out to the SIP Provider.

OK - I'll check with Voxtelesys. Just want to confirm, there aren't any adjustments I need to make on the pfSense for this set up?

 

[ChrisC_3CX]

Just want to confirm, there aren't any adjustments I need to make on the pfSense for this set up?

If you're talking about the 3CX SBC site then not really. The use of the SBC negates the need for remote firewall configuration due to the fact that the SBC is the one that initiates the connection to the PBX meaning it's an outbound connection. Since you can hear the user's audio on the recording it means that it's already left the SBC site so the firewall there didn't block anything, also, since the recording has no audio of the external caller you immediately know that it's not the SBC's firewall blocking it.

 

[Kevin@voxtelesys]

Hi AlphetaCS, we have your ticket on our end and will work with you to help resolve any issues.

 

[Kevin@voxtelesys]

Just follow up here, Voxtelesys worked with the AlphetaCS and during testing found the poor quality for coming from the Avaya (old carrier) on the call forward to the customers temporary number while the porting is happening.