Intermittent Silent Outgoing Calls

[BCTech]

Hello,
We have a relatively new setup running the latest enterprise version on Gradwell SIP trunks. The 3cx server sits on VMWare 7 and has a single network adapter on VLAN 2 10.20.24.0/21. The phones(A mixture of Yealink T46S and Fanvil 3XU) also sit on VLAN 2. A Smoothwall firewall sits in front of the server and acts as the gateway. It has the required port forwards enabled and passes the firewall tests. The internal network VLAN 1 has the same rules in place to allow access to the server for those using the web client.

We are getting issues whereby the outgoing caller hears the line ringing but when it is picked up the caller at the other end can hear us but we cannot hear them. We have experimented with turning off IPS/IDS, allowing all ports etc on the firewall but still the problem persists. All firewall traffic is logged and not seeing any blocks. Really out of ideas. Our reseller is working on this as well but additional help is appreciated as it has been ongoing for over a week and no closer to a solution

I've tried call recording on a problem call and the recording is also silent

Thanks

Robbie

 

[AWS2P]

Your audio problem is occuring only with outside calls? internally no problems?
Is your SIP provider 3cx supported?

We have experimented with turning off IPS/IDS

No idea what does this means

 

[BCTech]

Your audio problem is occuring only with outside calls? internally no problems?
Is your SIP provider 3cx supported?

No idea what does this means

Outgoing external calls but there have been some internal extension to extension issues. Internally all traffic is open.

I have had someone using their personal device at home have the issue too.

IPS/IDS intrusion prevention/detection. As it doesn't appear to be a traditional rule firewall rule block we tried seeing if these settings were causing a block

 

[leejor]

Are there any issues with incoming calls?
Have you considered the use of Wireshark, perhaps at the last point, on your network.
Do you just have the one trunk group to test with?

 

[BCTech]

Are there any issues with incoming calls?
Have you considered the use of Wireshark, perhaps at the last point, on your network.
Do you just have the one trunk group to test with?

Incoming from external are fine I think although possibly one report but that is not enough to make a judgement.

We've done a wireshark on 3cx at the time of an effected call this has gone to our provider as don't know how to diagnose those. We can wireshark at the phone if it might help

 

[BCTech]

Just to add when we turned off IDS/IPS on the firewall it did free up some phones that had a persistent problem however it has just moved the problem to others.

Reading my notes the internal to internal calls are silent for the recipient possibly a different issue?

Thanks

 

[AWS2P]

Are your phones all on same VLAN ?
No SIP ALG on your Router/firewall?
If you already have audio problems on LAN then this is most probably network related
Do you use POE switchs ?

 

[JohnS_3CX]

From your description it sounds like the network might be the root of the problem.

The audio ports range must be open entirely, in a persistent manner (9000-10999) so that as the PBX increases the port with each new calls, you dont end up on a blocked port. The firewall checker will test the beginning and end of ports, but it the ones in the middle are not open then you will have intermittent issues

 

[BCTech]

From your description it sounds like the network might be the root of the problem.

The audio ports range must be open entirely, in a persistent manner (9000-10999) so that as the PBX increases the port with each new calls, you dont end up on a blocked port. The firewall checker will test the beginning and end of ports, but it the ones in the middle are not open then you will have intermittent issues

There firewall rule currently is to allow any traffic from any internal network to the 3CX server. The phones are in the same VLAN as the 3cx server. No ports are blocked or shown as blocked in the logs

 

[BCTech]

Are your phones all on same VLAN ?
No SIP ALG on your Router/firewall?
If you already have audio problems on LAN then this is most probably network related
Do you use POE switchs ?

Phones are on the same VLAN and IP range as the 3CX Server.

SIP Proxy/Gateway is turned off on the firewall.

We use HP/Aruba POE switches

I'm still quantifying the LAN calls.

Thanks