The Cisco ISR 4000 family hosts the Cisco NIM cards 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 Cisco ISR 4000 allow for flexible configurations. NIMs support OIR reducing downtime required for new or replacement modules.

The NIM cards include 2-port and 4-port foreign exchange station (FXS) direct inward dial (DID) foreign exchange office (FXO) a combination of 2-port FXS and 4-port FXO 4-port ear and mouth (E/M) and 2-port and 4-port basic rate interface (BRI). BRI cards support only voice features.