1-2 second audio loss randomly during external calls

[rugosus]

Hi All,

We have set up the free 2-line version (v14 SP2) running on an SBS2011 server. The server has a low number of users, a good spec, and max RAM of 32GB. We have 5 extensions (4 x Polycom 335) and one Siemens Gigaset wireless. The SIP trunk provider is Sipgate UK. Our internet connection is leased line 40Mb fibre with a Sonicwall TZ210. Followed all the instructions for using Sonicwall with 3CX as shown on 3CX blog (e.g. no consistent NAT or SIP transformations), including the firmware version to support 3CX to disable source port remapping. All the DNS/firewall tests on the 3CX management homepage pass OK.

The problem is that on external calls we lose the audio for 1-2 seconds but not at regular intervals (as far as we can tell). We aren't experiencing intermittent connection problems with any other WAN traffic, and we have previously used the exact same Sipgate SIP trunk and Sonicwall router with a hardware PBX (Pheenet iPBX-011) for several years with no call quality problems. Internal calls are fine, and audio quality on all calls is great (other than these drops).

Please can someone point me in the direction of factors to look at which might affect this as the problem?

On a separate note, is it possible to buy support on a 2 line system that is already set up? Or is there an option for per-incident pay-as-you-go support for issues like this?

Thanks,

Paul

 

[lneblett]

I do not have a specific answer to your issue, but -

SBS2011 does not show on the supported OS list for V14. There was a post during the initial Beta trials about its use and the response at that time was that it had not been tested and therefore 3CX could not support it. Given that it does not show on the current list, I can only assume that the situation has not changed or that perhaps it had been tested and found to have issues.

You might try and install on a system running WIN7 or WIN10 Professional to see if the issue persists. If it does, then a Wireshark capture may shed some light or you may need to validate the settings/firmware of the Sonicwall to include the Hotfix.

 

[leejor]

Seeing as you aren't having any issues internally, you might want to enlist help from your provider. They may just point a finger at your ISP as a possible cause (and they may be right), but if you don't ask...

 

[rugosus]

Thanks guys. Points duly noted. SBS is sometimes tricky in terms of 3rd party software providers because they have a lot of MS software running on them already, but we find that most things are fine unless they have a specific port or software module clash.

We don't have a system provider as we installed it ourselves - hence the other part of my question about how we can get support on 2 line system like this.

Cheers,

Paul

 

[lneblett]

I do not believe that you can get support directly from 3CX (even under a paid program) as they will only provide it given that you use supported OS and hardware. You will have to find a reseller who is willing to take it on; otherwise the support from the forum is the only readily available resource.

I believe that leejor is suggesting that you might ask your SIP provider to render some aid. They can usually do a capture and advise if they see anything out of sorts.

The only other way I can think of to narrow down the issue is to do a port mirror of the WAN and run a wireshark while also running a wireshark on the 3CX side. In this manner you can see the RTP traffic as it hits the WAN and then again when reaching 3CX. If there is no loss on the WAN and it shows on the LAN, then the issue is the router or network.

You did not mention if the audio loss was at both ends or only at one (yours).

3CX does not like certain apps on the same machine, most notably Exchange or other highly intensive programs like SQLserver.

 

[rugosus]

Thanks Ineblett - and sorry for delay in replying. I will try some of those things and see how I get on.

Paul