The Draytek 2820VN router is compatible with both ADSL/ADSL2+ and cable technologies. The 'VN' model support standard SIP compliance, with up to 12 simultaneous registrars, plus multiple codec support. Gigabit port on the router provides a faster link where needed, be that to a gigabit switch or to a server on the network. The VN model has twin VoIP ports with PSTN pass-through, Compatible with ISDN2e lines (PtMP/BRI only) and is ideal for ISDN Backup to main Internet connectivity.