Cisco Single-Wide High Density Analog Voice Service Module With 16 FXS And 2 FXO

The Cisco Single-Wide High Density Analog Voice Service Module is purpose-built to deliver scalable, reliable analog voice and fax connectivity directly into Cisco 4000 Series Integrated Services Routers (ISRs). With 16 FXS ports and 2 FXO ports, this high-density module enables enterprises, managed services providers, and service providers to bridge traditional telephony equipment and public-switched telephone networks (PSTNs) with modern IP-based communications. It is designed to simplify deployment, optimize call quality, and expand the reach of voice services across branches, contact centers, and hybrid environments. By integrating analog voice capabilities into the ISR, organizations can consolidate networking, reduce hardware sprawl, and leverage Cisco’s robust management tools to maintain consistent, high-quality telephony services alongside VoIP and Unified Communications (UC) deployments.

• High-density analog interface: 16 FXS ports for connecting traditional analog telephones, fax machines, and small office devices, plus 2 FXO ports for connecting to PSTN trunks. This arrangement consolidates multiple analog lines into a single, space-efficient module, enabling large deployments without expanding the router footprint. The FXS ports provide the voice interface for end-user devices, while FXO ports offer trunk connectivity to external telephony networks, enabling hybrid setups that blend IP-based calling with legacy lines for reliability and continuity.
• Direct PSTN integration with reliable fallback: The module enables direct PSTN origination and termination from Cisco ISRs, ensuring that business-critical calls and fax transmissions can traverse the traditional telephone network when needed. This direct integration supports continuity during IP network outages and can serve as a dependable backstop for important communications, such as regulatory compliance calls, emergency notifications, and enterprise-wide fax workflows.
• Seamless Cisco ISR integration: Specifically designed to slot into Cisco 4000 Series ISRs, it works with IOS XE to deliver cohesive call control, routing, and policy enforcement. Operators can leverage familiar Cisco tools to manage dial plans, voice quality, security policies, and QoS, ensuring that analog and IP-based voice services share a single, centralized management plane. The module complements data, security, and collaboration features across the ISR platform, enabling unified administration for mixed voice environments.
• Enterprise-grade reliability and signaling compatibility: Built for robust performance in enterprise settings, the module supports standard telephony signaling and assessment capabilities to deliver clear, dependable voice and fax services. It is designed to operate within Cisco’s recommended environmental and power parameters, with firmware and hardware tested to sustain consistent call quality, low jitter, and predictable latency. This reliability translates into a stable user experience for phones, fax devices, and any legacy equipment connected through FXS/FXO ports, even in distributed locations.
• Future-proof scalability and flexible deployments: As organizations grow, the module scales to handle more analog endpoints and trunk connections without requiring a separate gateway. Its high-density design supports expanded voice deployments, centralized dialing plans, and easier integration with CUCM, Unity, and other Cisco UC components. The module’s architecture allows for straightforward firmware updates and configuration changes via Cisco management interfaces, helping IT teams adapt to evolving requirements, whether expanding call capacity, enabling new fax workflows, or supporting hybrid IP-telephony strategies.

Technical Details of Cisco Single-Wide High Density Analog Voice Service Module

• Interfaces: 16 FXS analog telephone ports for end-user devices and 2 FXO analog trunk ports for PSTN connectivity.
• Form factor: Single-wide high-density service module designed to fit Cisco 4000 Series ISRs.
• Compatibility: Optimized for use with Cisco 4000 Series Integrated Services Routers and IOS XE-based environments.
• Signaling and compatibility: Supports standard telephony signaling on FXS/FXO interfaces; designed to work with established PSTN and voice gateway workflows within Cisco deployments.
• Management and deployment: Integrates with Cisco management tools and policy frameworks, enabling centralized configuration, monitoring, and maintenance alongside other ISR-based services. (Exact power, environmental specifications, and supported IOS XE versions should be confirmed against official Cisco documentation and SKU-based specifications.)

How to install Cisco Single-Wide High Density Analog Voice Service Module

Installing this module in a Cisco 4000 Series ISR is a straightforward process that follows standard Cisco hardware installation practices. Plan your installation in advance by verifying compatibility with your specific ISR model and IOS XE version, ensuring you have the correct rack space, power, and cooling for reliable operation. The steps below outline a typical installation workflow that aligns with Cisco’s recommended procedures for high-density service modules.

• Power down the router and unplug power sources as specified by Cisco hardware safety guidelines. Remove the router cover if required and prepare the chassis for module insertion.
• Insert the module into an available single-wide slot in the Cisco 4000 Series ISR, ensuring it seats firmly and the retention mechanism engages securely. Confirm that the slot is compatible with the module’s form factor and that no other modules obstruct the hot-swap process.
• Reconnect power and verify that the router initializes with the new module recognized by the system. Use the Cisco IOS XE command-line interface to confirm the module is detected and that all FXS and FXO ports are online and ready for configuration.
• Attach the analog lines: connect analog phones and fax devices to the 16 FXS ports and connect PSTN trunks or line side equipment to the 2 FXO ports, following your organization’s telephony design and regulatory requirements.
• Configure voice services in IOS XE: define dial peers, voice gateways, and routing policies to integrate the analog module with your IP telephony topology. If you are using Cisco Unified Communications Manager (CUCM) or other IP-PBX systems, establish appropriate central routing, digit maps, and failover strategies to ensure seamless voice continuity between IP and analog paths.
• Test end-to-end calls and fax transmissions to validate voice quality, signaling reliability, and fax pass-through or T.38 behavior as applicable. Monitor call quality metrics and adjust QoS settings to prioritize voice traffic and mitigate jitter or packet loss in mixed networks.
• Document the configuration, including port assignments, dial peers, and trunk connections, so future changes or troubleshooting can be performed quickly by network engineers or support teams.

Frequently asked questions

• Q: How many analog ports does this module provide? A: It provides 16 FXS ports for analog devices such as telephones and fax machines, plus 2 FXO ports for PSTN trunk connections.
• Q: What platforms is this module compatible with? A: It is designed for Cisco 4000 Series Integrated Services Routers and works with Cisco IOS XE-based environments. Check your router model and IOS XE version for exact compatibility.
• Q: Can I use these ports for fax over IP? A: The module supports analog fax devices via FXS ports. Fax reliability over IP networks may depend on configuration details such as T.38 settings and network QoS; plan accordingly for best results in your environment.
• Q: Do I need any special licenses? A: Basic analog voice functionality is available with standard IOS XE; certain advanced UC features or CUCM integrations may require appropriate licenses according to Cisco licensing policies.
• Q: Is the module hot-swappable? A: Yes, Cisco high-density service modules are designed for field replacement without powering down the entire router, but follow Cisco maintenance guidelines and safety procedures when performing hot-swaps.