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Home Products Telephony FXS/FXO POTS FRM220-FXO/FXS-4 POTS Converter

FRM220-FXO/FXS-4 POTS Converter

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FRM220-FXO/FXS-4 POTS Converter

FRM220-FXO/FXS-4 POTS Converter

FRM220-FXO/FXS-4 is a 4 channel POTS (Plain Old Telephone System) over fibre converter/extender. The four POTS connection uses a standard RJ-11C modular connectors for each copper pair connection. A pair of FRM220-FXO/FXS-4 is required to implement an end to end system. FXO mode connects to a telephone line (PSTN) or PBX station line and has ability to detect ringing voltages and to act as a telephone. FXS mode is the reciprocal unit and has ability to act as PSTN and connects to a telephone device. When the FRM220-FXO/FXS-4 card is placed in the FRM220 rack with SNMP management, in-band management allows configuring and viewing the card and remote converter's status, type, version, fibre link status, on hook status and alarms. When placed in a single slot chassis and used standalone without management, the card may be configured by DIP switch.

FRM220-FXO/FXS-4 POTS Converter schematic


  • Extend telephone voice transmission up to 120km over fibre
  • Network management via terminal, web or SNMP in FRM220 chassis
  • Supports telephone voice transmission
  • Supports caller ID Pass-Through
  • Supports FXS to FXS hot line


Optical Interface:

  • Connector: SFP-LC
  • Fibre: MM 62.2/125μm, 50/125μm; SM 9/125μm
  • Distance: MM 2km, SM 15/30/50km; WDM 20/40km
  • Wavelength: MM 1310nm, SM 1310, 1550nm; WDM 1310Tx/1550Rx (type A); 1550Tx/1310Rx (type B)

Indications: LED (Power, FX Link, Phone Act, Test)
Power Input: 12VDC
Power Consumption: < 5W
Dimensions: 155 x 88 x 23mm (D x W x H)
Weight: 120g
Temperature: 0 ~ 50°C (Operating), -10 ~ 70°C (Storage)
Humidity: 10 ~ 90% non-condensing
Certification: CE, FCC, RoHS compliant
MTBF: 65,000 hrs

Electrical Interface:

  • Connector: RJ-11
  • FXO mode:
    • Impedance: 600 ohms
    • Coding: 16 bits liner
    • Loop Current: 10~100mA
    • Ring Frequency: Acceptable 20 ~50Hz
    • Insertion Loss: 0.0 ± 1.0dB at 1000Hz
    • Impedance: 600 ohms
  • FXS mode:
    • Coding: 16 bits liner
    • Dial: DTMF and Dial Pulse
    • Battery Source: 48VDC ± 4V
    • Ringing Waveform: Sine wave
    • Ringing Frequency: 20/25/30/35/40/45/50 Hz selectable
    • Ring Cadence: FXS to FXS : On / 1 sec, Off /2 sec
    • FXO to FXS: Reproduces the cadence detected by FXO
    • Insertion Loss: 0.0 ± 1.0dB at 1000Hz
    • REN: 4.0B(Ring Equivalence Number)