Cisco offers 1-Port ISDN with NT-1 WAN Interface Card. Customers can configure two these cards in a single mixed media network module that provides up to two Ethernet ports and two BRI ports on a single network module. In a two-slot chassis, a centralized small office can now support up to ten incoming BRI connections and have two Ethernet connections on the back end. Later, as the office grows, the Cisco 3620 router can be deployed elsewhere and a Cisco 3640 router can have up to 26 incoming BRI connections with two Ethernet connections to support local LANs.