VPN
If you need to connect to your office's Virtual Private Network, the 604 can support 50 IPsec, 20 PPTP, and some number of L2TP pass-thru sessions. Sessions can be simultaneously established to multiple remote VPN gateways, too. Mapping of LAN based VPN servers for all three VPN protocols is also handled.
Note also that you can enable/disable VPN pass through for IPsec and PPTP protocols. Curiously, there's no enable control for the L2TP VPN protocol that's also supposed to be supported, so I'll assume that it's always on.