We have an RVS4000 router at two ends of a VPN tunnel. The VPN tunnel is working fine, however a phone at the remote site drops calls, even though they sound clear and unblemished. I have set highest priority on the port the phone is hooked up to at the remote site, and have set a priority for upload traffic on both routers, but the phone stills drops calls after 2 to 3 minutes. Do you have any suggestions regarding settings to make sure the phone works?