Offering a single ISDN BRI S/T interface, this WIC may require an external Network Termination 1 (NT1), depending on the region of the world. The WIC inserts into a mixed-media network module or directly into the WIC slot on the Cisco 1600, 1700, 1800, 2600, 2800, 3600, 3700, 3800 Series chassis. The ability to add BRI connectivity through a WIC enables administrators to maximize valuable slot space while providing additional connectivity options, such as Ethernet, on the same module.