Oneway Audio on LAN, Traces have Audio, MixMon not

Hello Community,

I have a very frustrating and intermittent problem that we’re dealing with and have reached my wits end. :smile: We have pcap traces running 24/7. The PABX has been working well for more than a year.

From the traces and user experience this the problem:

We have intermittent One Way Audio, but always in the pattern that the Caller (A) has 2 way audio but that the Callee (B) has 1 way audio. From the traces on the PABX, Caller A to PABX both RTP streams are present. From PABX to Caller B, only Caller B’s stream is present. When listening to the MixMon recordings, there is only one way audio.

So the RTP reaches asterisk, but obviously asterisk does not recognise it or is upset with it and i) does not forward it on and ii) does not record the offending stream.

Any advice on debugging this problem will be much appreciated!




Asterisk 1.8.29 with FreePBX and Queuemetrics.
Phones in Two Subnets: (VLAN1/Native VLAN) and (Voice VLAN)
All the phones are Snom 710 - snom710-SIP
All calls G711A