One-way Audio, very intermittent and with timeout

Hi all,

after we managed to rule out all basic one way audio issues (native bridging, codec allow/disallow, NAT problems), a new and very intermittent one way issue has just occured. Persons who make 10-20 phone calls a day have not complained yet, but those using the phone more heavily suffer from it.
It is not a matter of calling / called party, but just of inside phone vs remote phone.
When the problem comes up, the remote person can hear our folks talk, but we cannot hear the remote person.
This only occurs after some time, one minute or more.

Anyone ever had such an issue? The problem in packet inspection would be that I can capture one or two whole days without a single incident. So I’d like to check anything possible before going this last step.

By the way: Asterisk 1.6 on LAN together with Snom 320 phones; SIP via using a Vigor draytek router with no explicit VoIP QoS settings


I don’t know if it will help you but we had a similar issue earlier this year - it had to do with the upload speeds of our ISP.

I noticed the upload speed when we had issues with the phones was quite low.

We upgraded our plan with more bandwidth and the issue resolved itself.