Voice network module Cisco NIM-2FXO — 2 FXO analog voice ports for Cisco ISR

The Cisco NIM-2FXO is a voice network interface module that provides two FXO analog voice ports for installation in compatible Cisco Integrated Services Routers (ISR). Designed to add PSTN and analog trunk connectivity to ISR platforms, this module enables traditional analog line access for voice calls, fax machines and voicemail systems in branch and legacy-telephony environments. The product integrates with Cisco routing platforms to extend telephony capabilities where analog lines are required.

Advantages

The module offers two FXO ports in a compact Network Interface Module form factor, allowing straightforward installation into supported Cisco ISR chassis. It preserves existing analog PSTN investments by enabling connectivity between router-based voice systems and public telephone networks. The NIM-2FXO supports standard analog voice applications such as inbound/outbound calling and fax passthrough when used with appropriate router voice features and configuration.

Suitable for

• Small branch offices requiring PSTN/analog trunk access
• Sites with legacy analog telephony or fax devices
• ISR deployments that need simple analog line integration

Key specifications

• Port type: 2 FXO analog voice ports
• Form factor: Network Interface Module (NIM) for Cisco ISR
• Intended connectivity: PSTN/analog trunk access for voice and fax
• Compatibility: Designed for compatible Cisco Integrated Services Router platforms

How to use

Install the NIM-2FXO into an appropriate NIM slot on a supported Cisco ISR according to the router hardware installation guide. Connect the analog PSTN lines to the FXO ports using standard telephone cabling. Configure the router’s voice features and dial-plan to recognize the FXO interfaces and to route calls between IP telephony and the analog network. Ensure firmware and IOS versions on the ISR are compatible with the module and follow Cisco configuration examples for FXO integration.

Usage recommendations

Verify compatibility with your specific ISR model and IOS release before deployment. Use the module in environments where limited analog trunk capacity is sufficient; for higher density analog needs, consider other aggregation options. For reliable fax operation, enable and test fax passthrough or fax-relay features supported by the router platform.