[Freeswitch-users] Noise on line, does not show up in recordings

Sam van Herwaarden svanherwaarden at precisionag.org
Tue Jun 23 12:45:54 UTC 2020

Hi Avi,

Thanks a lot for your reply. I find it a bit hard to describe the noise, so
I made a recording. This is audio that I recorded when calling into the
system over skype, the noise is around second 27:
This is the same audio when using record_session on FreeSWITCH:

It's actually not an SIP setup - the system runs over PRI. It uses a
Sangoma A104 card with the wanpipe Sangoma driver and FreeTDM. So maybe
there is something going on at that point in the stack (I hadn't considered
that - thanks!). The setup is controlled using mod_erlang_event (though I
suspect that's not relevant for this issue).


On Tue, Jun 23, 2020 at 2:21 PM Avi Marcus <avi at avimarcus.net> wrote:

> Just thinking out loud:
> If it's working locally, but not externally, that sounds like some sort of
> networking issue.
> But what do you mean by noise? Not garbly or dropped packets, but added
> noise?
> How are you listening to it, that's different than the recording? Are you
> on the LAN or over the internet?
> If you're on the WAN, it could be some sort of congestion.
> If you're on the LAN, it could be an actual bug with a jitterbuffer or
> something wrong with the network card/driver or local network.
> Possible debugging step: get both a local and/or remote PCAP capture. That
> will let us see the network part. Because the most local audio within
> freeswitch you are finding fine as per the recordings.
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