Description
The Cisco SM-X-24FXS/4FXO is a single-wide, fixed-port high-density analog voice service module designed for Cisco ISR 4000 Series routers. It enables seamless integration of legacy analog telephony devices and PSTN connections into modern IP-based voice infrastructures.
Featuring 24 FXS ports for analog endpoints and 4 FXO ports for PSTN or PBX connectivity, this module delivers enterprise-grade voice, fax, and modem services directly from the router. An onboard DSP eliminates the need for external voice processing modules while providing advanced voice features such as echo cancellation, voice compression, jitter buffering, and fax relay.
The SM-X-24FXS/4FXO supports high availability through online insertion and removal (OIR) and includes FXO failover bypass ports to maintain emergency calling during power outages. It is ideal for branch offices, contact centers, and distributed enterprise environments transitioning from analog to IP telephony.
| Specification | Details |
|---|---|
| SKU | SM-X-24FXS/4FXO= |
| Product Type | High-Density Analog Voice Service Module |
| Router Compatibility | Cisco ISR 4000 Series |
| Form Factor | Single-wide SM-X module |
| FXS Ports | 24 (analog phones, fax, modems) |
| FXO Ports | 4 (PSTN / PBX connectivity) |
| FXO Failover Bypass | Supported (4 ports) |
| DSP | Integrated onboard DSP |
| Voice Codecs | G.711, G.729a, G.726, G.722, iLBC, GSM-AMR |
| Fax Support | T.38 relay, fax pass-through |
| Modem Support | Modem pass-through |
| Signaling Protocols | SIP, H.323, MGCP, SCCP |
| Echo Cancellation | Up to 128 ms |
| Online Insertion & Removal | Supported |
| Interfaces | RJ-21 (FXS), RJ-11 (FXO) |
| Power Draw | ~79 W |
| Use Cases | Analog voice gateways, PSTN access, SRST, branch telephony |
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Return Policy (Short Summary)
We offer a 30-day return window for most unopened, factory-sealed items.
Returns must be authorized before shipping back and must include all original packaging and accessories. Opened or used items are not returnable unless defective.
Some products—such as custom orders, special-order items, audio gear, software, and LED video walls—are non-returnable. Non-defective returns may be subject to a 20–30% restocking fee, and customers are responsible for return shipping costs.
For damaged or incorrect items, please contact us immediately.
From Scope to Sign-Off
A structured delivery process designed to reduce risk and keep projects moving.
Plan
Discovery, site review, requirements gathering, and project alignment. We define scope, constraints, and success criteria before any design work begins.
- Discovery calls & stakeholder interviews
- On-site survey & infrastructure review
- Requirements & use-case documentation
- Project scope, timeline & milestone alignment
Engineer
System design, schematics, signal flow, BOM development, and documentation. Every project leaves this phase with a complete engineering package.
- AV system design & signal flow diagrams
- Equipment selection & BOM development
- Rack layout & control system design
- As-built documentation package
Deploy
Procurement, logistics, installation, programming, commissioning, and training. We own the delivery from first shipment to final handoff.
- Authorized procurement & logistics coordination
- Physical installation & cable management
- Control system programming & configuration
- Commissioning, testing & end-user training
Support
Monitoring, maintenance, lifecycle planning, and long-term service agreements. We stay engaged long after project close.
- 24/7 remote system monitoring
- Preventive & reactive maintenance
- Technology lifecycle & refresh planning
- Long-term service level agreements
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