Cisco C931-4P 1 SIM Cellular, Ethernet, ADSL2, VDSL2+ Modem/Wireless Router

The Cisco C931-4P is a compact, fixed-configuration router from the Cisco 900 Series ISR family designed to deliver secure, reliable connectivity for remote offices, small to mid-size businesses, and service-provider deployments. With integrated security and threat defense, it combines DSL, Ethernet WAN, and a cellular LTE backup in a single device, helping organizations maintain continuity even when one link experiences disruption. The C931-4P is engineered for environments where space is at a premium, yet the demand for robust broadband, Metro Ethernet, and wireless WAN connectivity remains high. The result is a versatile platform that can serve as a gateway, a security-centered edge router, and a Wi‑Fi-capable business router in one compact chassis.

• All-in-one WAN versatility with cellular backup: The Cisco C931-4P supports multiple ingress options including ADSL2+, VDSL2+, Ethernet WAN, and a dedicated SIM slot for cellular LTE backup. This blend of fixed wired connectivity and wireless failover ensures uninterrupted remote-site access and business continuity, even when one link drops or experiences congestion. Designed for hybrid networks, it lets you balance costs and performance by routing traffic over the most appropriate path in real time.
• Integrated security and threat defense: Cisco’s 900 Series ISR devices fuse performance with security. The C931-4P features a layered security model, including a stateful firewall, VPN capabilities (IPsec), and threat defense to help shield networks from known and emerging vulnerabilities. This consolidation reduces the need for separate security appliances at the edge while providing centralized policy enforcement for branch offices and service-provider environments.
• Fixed-configuration reliability in a compact footprint: Built as a fixed-configuration router, the C931-4P is designed to fit in tight spaces such as small cabinets, network closets, or onto a shelf in a remote location. The device’s fanless or low-noise operation (depending on model) helps it blend into quiet office environments while delivering steady, predictable performance without requiring extensive cooling or maintenance.
• Integrated wireless routing capabilities and LAN access: In addition to wired WAN options, the C931-4P provides wireless router functionality to support local devices, guest access, and mobile devices within the branch. The device can provide dependable LAN services through multiple high-speed Ethernet interfaces, enabling smooth distribution of data to printers, workstations, VoIP phones, and other wired and wireless endpoints.
• Easy deployment, centralized management, and scalable service delivery: With Cisco IOS XE software underneath, the C931-4P supports familiar management interfaces, including CLI and GUI-based configuration, SNMP for monitoring, and secure remote management. This makes it easier to roll out across multiple sites, apply consistent configurations, and scale from a single branch to a distributed footprint with predictable administration.

Technical Details of Cisco C931-4P

• Modem and WAN interfaces: Combines ADSL2+ and VDSL2+ modem support with 1 x Ethernet WAN port and a dedicated 1 SIM cellular slot for LTE backup, enabling diverse connectivity options in one device.
• LAN and wireless capabilities: Provides multiple LAN ports (Gigabit-class Ethernet) for connected devices and up to integrated wireless routing support for local devices, enabling flexible deployment in environments where both wired and wireless access are required. The wireless capability is designed to support typical small-business use cases such as guest networks and mobile device connectivity without compromising security.
• Security and threat defense features: Includes a layered security framework with stateful firewall capabilities, VPN support (including IPsec), and threat defense measures to help mitigate eavesdropping, spoofing, and unauthorized access while maintaining performance for business-critical applications.
• Management and provisioning: Runs Cisco IOS XE software with a familiar CLI/GUI for configuration and monitoring. Supports secure management protocols and logging, enabling centralized policy enforcement, remote provisioning, and integration with standard network management workflows.
• Form factor and reliability: Fixed-configuration router designed for compact deployment in edge locations, data closets, or small offices. A silent or low-noise profile makes it suitable for workspaces, while the rugged engineering supports continuous operation in diverse environments.
• Power and environmental considerations: Engineered for reliable operation with standard power inputs suitable for office and telecom environments. Built to operate in typical climate conditions found at enterprise sites without requiring elaborate cooling or enclosure solutions.
• Typical use cases: Excellent for remote office gateways, branch connectivity with LTE backup, service-provider edge deployments, and mixed-network environments where DSL, Ethernet, and cellular WAN are needed alongside secure, managed routing.

How to install Cisco C931-4P

• Plan and prepare: Before installation, confirm the site requirements including DSL service type (ADSL2+ or VDSL2+), Ethernet uplink needs, and the preferred cellular provider for the LTE backup. Ensure power availability and a secure mounting location protected from dust and moisture.
• Insert SIM and connect the WAN interfaces: Route the DSL line to the appropriate ADSL2+/VDSL2+ port and insert the SIM card into the dedicated cellular slot. Connect the Ethernet WAN port to your upstream network or ISP modem where applicable. If you intend to use wireless routing, enable and configure wireless settings as part of initial setup.
• Power up and access the management interface: Apply power and connect a computer to one of the LAN ports. Access the device's management interface via the default IP address (as provided in the product documentation) using a web browser or through the CLI. If required, connect via console for initial configuration.
• Run initial setup and provisioning: Use the on-device wizard or CLI to set up basic network parameters, including WAN/LAN interfaces, security policies, VPN settings, and wireless credentials. Establish failover rules so traffic can automatically switch between DSL, Ethernet WAN, and cellular paths as needed.
• Define security policies and routing preferences: Implement firewall rules, VPN tunnels, intrusion prevention, and access control lists (ACLs) aligned with your organizational security posture. Configure NAT, QoS, and traffic shaping if necessary to prioritize business-critical applications.
• Test connectivity and monitor health: Verify Internet reachability across both primary and backup links. Test VPN connectivity to remote sites, and confirm wireless clients can access the network. Monitor link status and device health via the management interface or integrated dashboard.
• Documentation and ongoing management: Save the configuration, back up the startup-config, and document all settings for future maintenance. Schedule firmware checks and security updates through Cisco’s recommended update channels to ensure ongoing protection and feature support.

Frequently asked questions

• Q: Does the Cisco C931-4P support LTE backup using the SIM card?
  A: Yes. The unit includes a dedicated SIM slot for cellular LTE connectivity, providing a reliable backup path for WAN when DSL or Ethernet links are unstable or unavailable.
• Q: What kinds of security features are built into the C931-4P?
  A: The device offers a layered security approach that includes a stateful firewall, VPN support (IPsec), and threat defense capabilities to help protect against known and emerging threats at the network edge.
• Q: Can I use this router for both DSL and Ethernet WAN connections at the same time?
  A: Yes. The C931-4P is designed to support multiple WAN interfaces, enabling flexible routing, load balancing, and automatic failover between ADSL2+/VDSL2+, Ethernet WAN, and cellular paths.
• Q: Is wireless connectivity available on the C931-4P?
  A: The device supports integrated wireless routing capabilities suitable for small office or remote-site deployments, allowing wireless clients to connect while keeping security policies in place.
• Q: How is the device managed and configured?
  A: Management is provided through Cisco IOS XE, offering both CLI and GUI options. It supports secure remote management, SNMP for monitoring, and standard enterprise management practices.