Cisco 2-Port FXS/FXS-E/DID and 4-Port FXO Network Interface ModuleUnlock flexible voice connectivity within Ciscos 4000 Series Integrated Services Routers (ISRs) with this high density Network Interface Module (NIM). The module combines 2 ports of FXS FXS E DID and 4 FXO ports into a single, compact card that slots into Cisco 4000 Series ISRs with available NIM bays. Built for modern hybrid voice deployments, it lets you connect analog phones or Direct Inward Dialing (DID) capable devices while preserving your IP