4 Channel POTS over fibre


  • 4 channel POTS (Plain Old Telephone System) over fibre
  • Supports telephone voice transmission
  • Network management via terminal, web or SNMP in FRM220 (NMC)
  • Supports FXS to FXS hot line
  • Caller ID Pass-Through
  • FAX and Modem support


FRM220-FXO-4/FXS-4 are 4 channel POTS (Plain Old Telephone System) over fibre converter/extender. The four POTS connection uses standard RJ-11C modular connectors or each copper pair connection. A pair of FRM220-FXO-4/FXS-4 is required to implement an end to end system. FXO units connect to a telephone line (PSTN) or PBX station line and has ability to detect ringing voltages and to act as a telephone. FXS units are the reciprocal and have the ability to act as PSTN and connects to a telephone device.

POTS FXS FXO over fibre hotline

Two FXS cards may be connected back-to-back to provide a private "hot line". When the FRM220-FXO-4/FXS-4 cards are 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.


Item Description
Optical Interface

Connector SFP-LC
Fibre MM 62.2/125μm, 50/125μm, SM 9/125μm
Rate: 155Mbps
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)

Electrical Interface

Connector:  RJ-11
FXO model Impedance : 600 ohms
Coding : 16 bits liner
Loop Current : 10~100mA
Ring Frequency : Acceptable 20 ~50Hz
Insertion Loss: 0.0 ± 1.0dB at 1000Hz
Level Gain : TX 0dB, RX -3dB
FXS model Coding : 16 bits liner
Dial: DTMF and Dial Pulse
Provides 48VDC ± 4V to FXO
Ringing Waveform : Sine wave
Impedance : 600 ohms
Ringing Frequency :   20/25/30/35/40/45/50/55 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)
Level Gain : TX 0dB, RX -3dB


LED (Power, FX Link, Phone Act, Test)

Power Input


Power Consumption

< 6W (FRM220-FXO-4)
< 12W (FRM220-FXS-4)


Card: 155 x 20.8 x 88mm (D x W x H)




0 ~ 50°C (Operating),
-10 ~ 70°C (Storage)


10 ~ 90% non-condensing




65,000 hrs

Ordering Information

Order Code Description
FRM220-FXO-4 4-port FXO fibre converter card (SFP-LC)
FRM220-FXS-4 4-port FXS fibre converter card (SFP-LC)

More Information

Chassis and mounting options for the FRM220 family.

AC and DC power options available.  See individual products for further details.

1 Slot standalone chassis for ISDN, voice or data modules, AC or DC
1 Slot chassis with DB9 console port for Ethernet, voice or serial cards
2 Slot Ethernet, ISDN and serial chassis with console port
2 Slot chassis manageable via NMC card
4 slot Ethernet, ISDN and serial chassis, 1U
8 Slot multi service rack, 1U
20 Slot multi function chassis with Ethernet, serial and ISDN, 2u
20 Slot Ethernet aggregation rack, 2u