The Cisco 2500 series family offers increased serial protocol flexibility and interface density. These models, supporting synchronous and asynchronous serial communications over multiple serial interfaces and services, are ideal for branch office environments and low-speed, wide-area network (WAN) concentration points. Rather than stacking several devices together or using a more expensive high-end router, the Cisco 2520 provides a cost-effective integrated solution.Users can connect a branch office local-area network (LAN) and multiple legacy serial devices to a corporate headquarters over a variety of high-speed primary and backup WAN services such as Frame Relay and Integrated Services Digital Network (ISDN). Alternatively, this model provides a low-cost way to internetwork multiple remote sites together over low-speed WAN lines such as X.25, connecting them to a corporate LAN or WAN backbone. With dial-in asynchronous capabilities, this model also provides an integrated solution for branches needing to connect telecommuters along with LAN and legacy traffic to the corporate network.