I currently have an issue at one of my sites, even with internal calls on our LAN. Basically, the calls go through fine, both sides can hear each other and then randomly it'll go silent for 5-10 seconds, and then back to normal. The phones are in their own dedicated VLAN, with QoS enabled. Latency between the server and handsets is 6ms maximum. Can anyone advise why these dropouts are happening?