Serial and asynchronous modules provide highly flexible connections for Cisco ® 1800, 1900, 2800, 2900, 3800, and 3900 Series Integrated Services Routers (ISRs). These modules help customers enable applications such as WAN aggregation, transport for traditional protocols, console servers, and dial access servers. Customers can mix and match modules to tailor cost-effective solutions for common networking problems such as remote network management, external dial-modem access, low-density WAN aggregation, transport for traditional protocols, and high-port-density support.