"The issue seems to occur regardless of how much traffic exists.
keep in mind that bandwidth is not as crucial a factor for VoIP quality as latency or RTT (round-trip time, commonly known as 'Ping'), the time in milliseconds for a ""ping"" packet to travel from your computer to the site and back again."
You can start by making a network trace of the VoIP traffic (with tcpdump or Wireshark). Wireshark then can process the trace and compute the jitter buffer or abnormal delay in media traffic (Check the Analysis menu). If you repeat this operation at several points, you may find what the problem is.
