Since few months, we are experiencing sound quality problem. The voice is clear but sometime we miss 1 or 2 seconds of the conversion, even on internal calls.
We are wondering if the issue is caused by our virtual server, our network our the phones. We have around 950 phones connected to our VitalPBX installation. Simultaneous active calls are usually between 15 to 25. Server has 4 vCPU and 4 GB of RAM. CPU usage on the dashbord is around 10% et 33% for memory. Most of our telephone are Yealink but we have some Cisco and Polycom as well. Active codecs on phones are G722, PCMU, PCMA and G729. Active codes on server are uLaw, aLaw and g729. Protocol is SIP. Switches are configured to honnor QOS DSCP marking.