Zeroshell should not be used solely for QoS implementation of VoIP on a network regardless of available bandwidth and latency of data circuits. The best practice and most common means to resolve issues like this with mixed data, video and voice traffic is to use Intelligent L2 Switching. This will include vlans (using 802.1q), Class of Service (802.1p) and trunking (802.3ad) on the switch. At layer 2 the switches are best left to handle control of latency and preferential services while leaving the zeroshell/router to handle the routing.