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:
https://drive.google.com/file/d/1r36iAvd-Ym_qWrw1x_tig1owvQqkO9Id/view?usp=sharing
This is the same audio when using record_session on FreeSWITCH:
https://drive.google.com/file/d/1scDSWlGc52PC9x8Ed5-OWQruZmdLnb_D/view?usp=sharing

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).

Best,
Sam

On Tue, Jun 23, 2020 at 2:21 PM Avi Marcus <avi@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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