The NP-4G series Network Processor Module (NPM) for the Cisco 4000 and 4500 routers provides four serial ports with G.703 interfaces. The NP-4G has four ports, it operates at speeds up to 2 Mbps per port, bi-directional, and has both balanced/120-ohm and unbalanced/75-ohm versions available. The NP-4G is typically used for high-speed WAN services between regional sites or between regional sites and headquarters.