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by Cisco
Product Line: Cisco SM-D-48FXS-E
Product Type: Voice Interface Card
Original price $0.00 - Original price $611.00
Original price
$0.00 - $611.00
Current price $611.00
Title: Used

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Product Description

The SM-D-48FXS-E Cisco module features 48 Foreign Exchange Station (FXS) ports, supporting on-hook voltage of -44 V and off-hook loop current of 25 mA for short-loop-length ports and 35 mA for long-loop-length ports, designed for high-density telecommunication needs. It is compatible with Cisco IOS Software Release 15.2(4)M2 or later and can be installed in specific slots of Cisco 3945, 3925, and 2951 platforms, offering FXS loop lengths up to 3000 ft for short and 11,000 ft for long loop length ports. Additionally, the module provides two RJ-21 connectors and supports Category 3 and Category 5 cabling, ensuring reliable connectivity and compatibility with a variety of network infrastructures.

Key Feature for the SM-D-48FXS-E

  • What is the maximum number of Foreign Exchange Station (FXS) ports available?
    The device supports up to 48 FXS ports.
  • Which Cisco IOS Software release is required for operation?
    Operation requires Cisco IOS Software Release 15.2(4)M2 or later.
  • How many RJ-21 connectors are present?
    There are 2 RJ-21 connectors.
  • What is the on-hook voltage provided by the FXS ports?
    The on-hook voltage is -44 V.
  • Can the FXS ports support extended loop lengths?
    Yes, 48 ports can be configured as FXS-Extended Loop Length.
  • What are the supported ring frequencies?
    Supported ring frequencies are 20, 25, 30, and 50 Hz.
  • What is the maximum loop resistance supported by the short-loop-length port?
    The short-loop-length port supports up to 600 Ohms.
  • What type of cable is recommended for use with the device?
    Category 3 and Category 5 cables are recommended.
  • What is the Ringer Equivalence Number (REN) loading for each port type?
    5REN per port for Short-Loop-Length Ports and 2REN per port for Long-Loop-Length Ports.
  • Which platforms support this device?
    Supported platforms include Cisco 3945, Cisco 3945e, Cisco 3925, Cisco 3925e, and Cisco 2951.

Product Review

The Cisco SM-D-48FXS-E module offers a high density of 48 FXS ports, which are all configurable as FXS-Extended Loop Length, making it suitable for a variety of voice applications within large enterprises or service provider networks. However, its requirement for Cisco IOS Software Release 15.2(4)M2 or later limits its compatibility to newer Cisco platforms, such as the Cisco 3945 and 2951 series, potentially excluding older infrastructure. Additionally, while it provides two RJ-21 connectors for easy scalability, the double-wide form factor may limit the number of modules that can be installed in a single router, affecting expansion capabilities.


The Cisco SM-D-48FXS-E is a high-density voice interface card designed for use in select Cisco Integrated Services Routers. This module provides 48 Foreign Exchange Station (FXS) ports for connecting analog devices such as fax machines, analog phones, and modems to a digital voice network. Each of these FXS ports can be configured as FXS-Extended Loop Length, supporting longer cabling distances between the network and connected devices. The module is equipped with two RJ-21 connectors, facilitating easy integration and connectivity. Additionally, it includes two Foreign Exchange Office (FXO) bypass ports, which are essential for failover to the PSTN in case of a power outage or network failure. The hardware is compatible with Cisco IOS Software Release 15.2(4)M2 or later, ensuring that it can operate efficiently with the latest network software features and security updates. This compatibility also guarantees seamless integration and operation within supported Cisco platforms, including the Cisco 3945, 3945e, 3925, 3925e, and 2951 routers. The SM-D-48FXS-E features on-hook voltage of -44 V and provides off-hook loop current of 25 mA for short-loop-length ports and 35 mA for long-loop-length ports, accommodating various operational requirements. - On-hook voltage of -44 V and off-hook loop current of 25 mA for short-loop-length ports and 35 mA for long-loop-length ports. - Compatibility with Cisco IOS Software Release 15.2(4)M2 or later. - Support for both loop-start and ground-start signaling formats. The module's ring frequency can be adjusted among 20, 25, 30, and 50 Hz, with the ring waveform being a sine wave if there is no DC offset. This flexibility ensures that the module can meet different global operational standards and user preferences. The FXS loop length capability is notable, supporting up to 3000 ft for short-loop-length ports and up to 11,000 ft for long-loop-length ports, which allows for versatile deployment scenarios across varied physical environments. The module is designed to work with both Category 3 and Category 5 cabling, and it utilizes RJ-21 and RJ-11 physical connectors for connectivity, offering wide compatibility with existing network infrastructure. Physically, the module has a double-wide form factor, fitting into DWSM slots Slot 4 in Cisco 3945 and 3945e, and Slot 2 in Cisco 3925, 3925e, and 2951 routers, ensuring a snug and secure fit into the compatible router models. The module's immunity standards include EN 55024, CISPR 24, EN50082-1, and EN 61000, ensuring its resilience against various environmental electromagnetic disturbances. Additional features include a configurable ring tone to meet different country requirements, caller ID support with on-hook transmission of Frequency-Shift-Keying, and FXS signaling formats that support both loop-start and ground-start signaling. The module also boasts a ring voltage of 54 Vrms into 5REN at zero loop length for short-loop-length ports and 62 Vrms into 2REN at zero loop length for long-loop-length ports, alongside FXS loop resistance of up to 600 Ohms for short-loop-length ports and up to 1400 Ohms for long-loop-length ports. These specifications are critical for ensuring reliable voice services and connectivity across a range of distances and operational conditions.


Item Number and MakerCisco SM-D-48FXS-E
Port DensityHigh
FXS Ports Quantity48
Adjustable Ports for Extended Distance FXS48
Connection Type2 RJ-21 Connectors
FXO Bypass Connections2
Minimum IOS Software VersionVersion 15.2(4)M2 or newer
Voltage When Not in Use-44 V
Current During Call (Short and Long Distance)25 mA (Short), 35 mA (Long)
Ring Signal Frequency20, 25, 30, 50 Hz
Type of Ring WaveformSine Wave without DC Offset
Maximum FXS Distance (Short)3000 ft
Maximum FXS Distance (Long)11,000 ft
Supported Cable TypesCategory 3, Category 5
Connector TypesRJ-21, RJ-11
Module WidthDouble Wide
Standards for ImmunityEN 55024, CISPR 24, EN50082-1, EN 61000
Compatible Cisco PlatformsCisco 3945, 3945e, 3925, 3925e, 2951
REN Capacity5REN (Short), 2REN (Long) per Port
Ring Voltage Capability54 Vrms at 5REN (Short), 62 Vrms at 2REN (Long)
Supported FXS SignalingLoop-Start, Ground-Start
Designated Slots for DWSMSlot 4 (3945, 3945e), Slot 2 (3925, 3925e, 2951)
Caller ID Transmission TypeFrequency-Shift-Keying when Idle
Ring Tone CustomizationAdjustable by Country
FXS Loop Resistance LimitsUp to 600 Ohms (Short), Up to 1400 Ohms (Long)

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