Voice prompt not being heard, lines goes dead.

[greengriff]

We've had a number of complaints from customers that our telephone line was dead, so we did some testing of your own. On approximately 50% of call attempts no voice prompt is heard (there is just silence) and then the the line goes dead, ending the call. We can see these calls on the 3cx log reporter listed as 'not answered', so they are definitely making it through from the 3rd party SIP trunk to our server.

Has anyone seen this kind of thing before and/or has a solution to the problem? If it's of any help we are running v.10.0.24018.2322

 

[lneblett]

How do calls come in to the system? How many simultaneous calls can you handle?

I am assuming in your case that you are using a SIP trunking agent. If I am correct, then it could be that the SIP messages are getting thru, but the RTP (voice) packets never make it and the call is subsequently dropped. Is this something new, given that you still have V10? Has anything changed?

Have you run the firewall checker and did all pass?

 

[greengriff]

Thanks for replying and apologies for my slow reply - our office is open long hours and I needed to wait for it to close before running the firewall checker. You are right your assumption about how calls come in. This is a recent problem (last week or so). Nothing has changed at all that I am aware of. Here are the results from running the firewall checker. All seems well. Do you have any thoughts on what the problem could be?:

3CX Firewall Checker, v1.0. Copyright (C) 3CX Ltd. All rights reserved.

<22:08:18>: Phase 1, checking servers connection, please wait...
<22:08:18>: Stun Checker service is reachable. Phase 1 check passed.
<22:08:18>: Phase 2a, Check Port Forwarding to UDP SIP port, please wait...
<22:08:19>: UDP SIP Port is set to 5060. Response received correctly with no translation. Phase 2a check passed.

<22:08:19>: Phase 2b. Check Port Forwarding to TCP SIP port, please wait...
<22:08:19>: TCP SIP Port is set to 5060. Response received correctly with no translation. Phase 2b check passed.

<22:08:19>: Phase 3. Check Port Forwarding to TCP Tunnel port, please wait...
<22:08:19>: TCP TUNNEL Port is set to 5090. Response received correctly with no translation. Phase 3 check passed.

<22:08:19>: Phase 4. Check Port Forwarding to RTP external port range, please wait...
<22:08:24>: UDP RTP Port 9000. Response received correctly with no translation. Phase 4-01 check passed.
<22:08:24>: UDP RTP Port 9001. Response received correctly with no translation. Phase 4-02 check passed.
<22:08:24>: UDP RTP Port 9002. Response received correctly with no translation. Phase 4-03 check passed.
<22:08:24>: UDP RTP Port 9003. Response received correctly with no translation. Phase 4-04 check passed.
<22:08:24>: UDP RTP Port 9004. Response received correctly with no translation. Phase 4-05 check passed.
<22:08:24>: UDP RTP Port 9005. Response received correctly with no translation. Phase 4-06 check passed.
<22:08:24>: UDP RTP Port 9006. Response received correctly with no translation. Phase 4-07 check passed.
<22:08:24>: UDP RTP Port 9007. Response received correctly with no translation. Phase 4-08 check passed.
<22:08:24>: UDP RTP Port 9008. Response received correctly with no translation. Phase 4-09 check passed.
<22:08:24>: UDP RTP Port 9009. Response received correctly with no translation. Phase 4-10 check passed.
<22:08:24>: UDP RTP Port 9010. Response received correctly with no translation. Phase 4-11 check passed.
<22:08:24>: UDP RTP Port 9011. Response received correctly with no translation. Phase 4-12 check passed.
<22:08:24>: UDP RTP Port 9012. Response received correctly with no translation. Phase 4-13 check passed.
<22:08:24>: UDP RTP Port 9013. Response received correctly with no translation. Phase 4-14 check passed.
<22:08:24>: UDP RTP Port 9014. Response received correctly with no translation. Phase 4-15 check passed.
<22:08:24>: UDP RTP Port 9015. Response received correctly with no translation. Phase 4-16 check passed.
<22:08:24>: UDP RTP Port 9016. Response received correctly with no translation. Phase 4-17 check passed.
<22:08:24>: UDP RTP Port 9017. Response received correctly with no translation. Phase 4-18 check passed.
<22:08:24>: UDP RTP Port 9018. Response received correctly with no translation. Phase 4-19 check passed.
<22:08:24>: UDP RTP Port 9019. Response received correctly with no translation. Phase 4-20 check passed.
<22:08:24>: UDP RTP Port 9020. Response received correctly with no translation. Phase 4-21 check passed.
<22:08:24>: UDP RTP Port 9021. Response received correctly with no translation. Phase 4-22 check passed.
<22:08:24>: UDP RTP Port 9022. Response received correctly with no translation. Phase 4-23 check passed.
<22:08:24>: UDP RTP Port 9023. Response received correctly with no translation. Phase 4-24 check passed.
<22:08:24>: UDP RTP Port 9024. Response received correctly with no translation. Phase 4-25 check passed.
<22:08:24>: UDP RTP Port 9025. Response received correctly with no translation. Phase 4-26 check passed.
<22:08:24>: UDP RTP Port 9026. Response received correctly with no translation. Phase 4-27 check passed.
<22:08:24>: UDP RTP Port 9027. Response received correctly with no translation. Phase 4-28 check passed.
<22:08:24>: UDP RTP Port 9028. Response received correctly with no translation. Phase 4-29 check passed.
<22:08:24>: UDP RTP Port 9029. Response received correctly with no translation. Phase 4-30 check passed.
<22:08:24>: UDP RTP Port 9030. Response received correctly with no translation. Phase 4-31 check passed.
<22:08:24>: UDP RTP Port 9031. Response received correctly with no translation. Phase 4-32 check passed.
<22:08:24>: UDP RTP Port 9032. Response received correctly with no translation. Phase 4-33 check passed.
<22:08:24>: UDP RTP Port 9033. Response received correctly with no translation. Phase 4-34 check passed.
<22:08:24>: UDP RTP Port 9034. Response received correctly with no translation. Phase 4-35 check passed.
<22:08:24>: UDP RTP Port 9035. Response received correctly with no translation. Phase 4-36 check passed.
<22:08:24>: UDP RTP Port 9036. Response received correctly with no translation. Phase 4-37 check passed.
<22:08:24>: UDP RTP Port 9037. Response received correctly with no translation. Phase 4-38 check passed.
<22:08:24>: UDP RTP Port 9038. Response received correctly with no translation. Phase 4-39 check passed.
<22:08:24>: UDP RTP Port 9039. Response received correctly with no translation. Phase 4-40 check passed.
<22:08:24>: UDP RTP Port 9040. Response received correctly with no translation. Phase 4-41 check passed.
<22:08:24>: UDP RTP Port 9041. Response received correctly with no translation. Phase 4-42 check passed.
<22:08:24>: UDP RTP Port 9042. Response received correctly with no translation. Phase 4-43 check passed.
<22:08:24>: UDP RTP Port 9043. Response received correctly with no translation. Phase 4-44 check passed.
<22:08:24>: UDP RTP Port 9044. Response received correctly with no translation. Phase 4-45 check passed.
<22:08:24>: UDP RTP Port 9045. Response received correctly with no translation. Phase 4-46 check passed.
<22:08:24>: UDP RTP Port 9046. Response received correctly with no translation. Phase 4-47 check passed.
<22:08:24>: UDP RTP Port 9047. Response received correctly with no translation. Phase 4-48 check passed.
<22:08:24>: UDP RTP Port 9048. Response received correctly with no translation. Phase 4-49 check passed.
<22:08:24>: UDP RTP Port 9049. Response received correctly with no translation. Phase 4-50 check passed.


Application exit code is 0

 

[lneblett]

A few more questions:

1. Do you have a fixed public IP?
2. Are you running STUN?
3. Is there a reason you are still running V10?
4. Are all internal calls OK?
5. Outbound calls are not similarly affected? They go through fine and no matter the duration of the call?
6. Is there only one NIC card installed in the system where 3CX resides?

On the surface, I am inclined to suggest that you should contact your provider and then arrange to duplicate your earlier testing while they are monitoring. It still sounds like RTP packets are not making it to the system; hence the reason no audio.

Ideally, you should be running V11 SP1, fixed IP, STUN is disabled and the firewall checker passes (v11 checker seems to be more robust in this area) and one NIC.