High bandwidth consumed by freepbx server

We use freepbx for our voip lines, and configured it using live IP provided by our ISP. But, at times our freepbx server takes lots of bandwidth which is creating a major issue. Also, a important thing I should mention that recently in our router QOS service, I have set xlite (this is the softphone we use) as a high priority. Is there any other issue than QOS things which create this issue.

My guess is that have an unpatched ntp service running, (fixes available on the intertubes), I wasn’t aware xlite had a specific QOS, you would have to be more specific as to what you did but also it is pretty well guaranteed that QOS is not your problem.