The BCM's WAN port is for the connection of a point-to-point T1 or Frame Relay connection. I'm not aware that it costs extra to activate it, though.
Most BCM's are ordered in a LAN/LAN only configuration. If you require a P-T-P T1 or FR connection, you would then order a WAN card and install it -- I don't believe that there are software keycodes for the activiation of the WAN blade.
Personally, in this situation, I'd buy a cheap Cisco 1700 series (or equivalent) router and terminate the P-T-P or FR circuit in the router and come into the BCM on LAN 2 from the router's ethernet port, if you need to. The router gives you more options and troubleshooting utilities, plus all your eggs aren't in one basket. There are situations when this wouldn't be the recommended configuration, but not usually.
