We highly recommend consulting an IT or network professional when configuring advanced network settings and equipment.The goal of configuring any router or firewall for use on 8x8 service is to prioritize VoIP traffic on your network and achieve optimum call quality. In the case of the ZyXELL ZyWALL USG-50, we want to. Enable FTP ALG.
Zywall Application Patrol License Search
Enable H.323 ALG. Enable SIP ALG. Add port 5199 as a SIP Signaling PortSince the ZyWALL USG-20 has a very similar interface, the instructions below apply to the ZyWALL USG-20 as well.Detailed instructions are available from ZyXELL here.