4-port Network Interface Module – FXO (Universal) NIM-4FXO is supporting for the Cisco 4000 ISR Series. The Cisco® 4000 Series Integrated Services Routers (ISRs) host the Cisco network interface modules (NIMs), which have evolved from the enhanced high-speed WAN interface card (EHWIC), increasing port density and module capability. Up to three integrated NIM slots on the 4000 Series allow for flexible configurations. The NIMs support online insertion and removal (OIR), reducing the downtime required for new or replacement modules.