Certain calls ring forever other calls have no audio

[AS19]

Hi,

I'm using 3cx and a GXW-4104 FXO gateway. There is no sip trunk provider who has local numbers where I live.

When placing an outgoing call from the 3cx system calls to certain numbers just ring forever and are never answered. The Call Log shows these calls as "Not Answered", the activity log for these calls looks just like a successful call. I can see in the activity log that the calls that failed matched the same outbound rule as the calls that succeeded. The numbers that ring always behave the same, we have never had a call to one of those numbers succeed.

We also occasionally have calls where with no audio when making an outside call. The person we are calling will say that their phone rang but there is no audio when they answer.


We had a 3cx expert come look at our system but he could not find any issues.


Any advice would be greatly appreciated.

 

[cobaltit]

So you haven't mentioned anything about 3CX version or how the device is configured. Please confirm you are on the latest 3CX version, if the gateway is local, and if you followed this guide for provisioning:

https://www.3cx.com/voip-gateways/grandstream-fxo/

It would be nice to know the firmware version of the gateway as well.

 

[AS19]

I'm running 3cx 16.0.910 on Linux.

Yes I followed the guide to provision the FXO gateway. 3cx automatically sets the "Register Expiration" on the FXO to 0, I've changed that to 120 minutes manually.

GXW-4104 firmware version is 1.4.1.5

 

[leejor]

When placing an outgoing call from the 3cx system calls to certain numbers just ring forever and are never answered. The Call Log shows these calls as "Not Answered", the activity log for these calls looks just like a successful call.

Are calls to these same numbers from other originations (your mobile) ever answered? In most cases, on a PSTN Gateway, the ring back tone (or any other audio) is coming from your PSTN provider.

You might want to see if there is any pattern to these calls. Are they (perhaps) using the same phone line, from the gateway?

The "no audio" issue is rare, when using a gateway, local to the server. Has this issue started recently, or has it been doing this from day one? If it started recently, were there any changes, or updates that happened about the same time?

 

[AS19]

Inbound calls seem to work fine. its just outbound calls to certain numbers that never go through. 3cx seems to think the calls were completed properly.

If I disconnect the PBX and hook a phone up to the same telephone line and then call the same number the call will go through. If I call the same number form my mobile the call goes through.

We are using phone lines dedicated to the FXO gateway, nothing else is connected to those lines.

When placing a call from 3cx to one of the affected numbers, I can't say if the phone that is being called actually ever rings or not, 3cx just plays its ringing sound for ever and when you hang up logs the call as not answered.

We have had the no audio issue since day one, certain people would call back and say their phone rang and when they answered there was no sound.

 

[AS19]

I think I fixed the issue with certain numbers not working. The 3cx expert who came to work on our system had enabled "Polarity Reversal" in the FXO gateway. Turning that off allowed me to call the numbers I know about that were not working.

I still need help figuring out the no audio issue.

 

[JohnS_3CX]

Hi AS19,

Try to go to trunks, select the Grandstream, and ensure PBX Delivers Audio is on (should already be on by default).

Can you confirm that the FXO is on the same LAN as the PBX? Is there any network equipment between them that may cause any audio ports to be blocked?

 

[AS19]

PBX delivers audio is enabled.

FXO and gateway are on the same network. No firewall rules that would interfere with PBX to FXO communications.

 

[JohnS_3CX]

Is it possible to replicate the issue (perhaps from a specific phone or towards a specific destination) and run a capture on the PBX while this is happening?

 

[AS19]

The no audio issue is intermittent. I wasn't able to replicate it for months, I just kept having people report it. Yesterday I had people from my office trying to call my mobile twice and there was no audio. When I called my office back from my mobile the audio was fine.

 

[AS19]

I also have "PBX delivers audio" enabled on every extension in an attempt to get the no audio issue fixed, having it enable has had no effect.

 

[JohnS_3CX]

that would not affect things, since the first point in the chain (trunk) has PBX delivers audio then phones will only reach the gateway via the PBX.

You could also consider running tshark in the background to keep capturing until a problematic call is "caught" and then checking it in WireShark