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4-Channel Phone with RS-485 Data

4-Channel POTS and Data to Fiber Installation Kits

VERSITRON’S 4-Channel POTS phone/data kits provide you with all the necessary equipment to convert 1 to 4 standard 2-wire analog phone signals to fiber optic cable as well as provide RS-485/422 data transmission. Both Multimode and Singlemode fiber are supported in simplex and duplex formats. The installation kits include:

  • FXO Tele-Data Modem – Exchange Side
  • FXS  Tele-Data Modem – Subscriber Side
  • Standalone or Rack-Mount Housing
  • 110VAC to 12VDC Power Supplies
  • 100 Meters of Multimode or Singlemode Cable in Simplex or Duplex

Our 4-channel tele-data modems have a digitizing process allows for a fully transparent fiber optic link. LED indicator lights are used for the telephone link status on the FXO and FXS modems. Their functions are:

  • LINK - Indicates the remote link is active and synchronized
  • SYSTEM - Indicates the system is active and configured (ready for operation)
  • TX - Indicates data is being transmitted
  • RX - Indicates data is being received
  • 1-4 - Indicates the status of the telephone line connected to Port 1 (On-Hook, Off-Hook, Ringing)

An RJ11 connector provides the copper interface for the telephone input and an RJ-45 connector provides the copper interface for the RS-485 or RS-422 data. LC fiber connectors provide the fiber optic interface.

Features of 4-Channel Phone Kit with RS-485 Data:

  • Extend 1 to 4 analog telephone lines and/or data
  • Analog audio signal 300Hz to 3.4Kz
  • RS-485/RS-422 Full-Duplex Data up to 64Kbps
  • LED indicators for Instant System Monitoring
  • Multiple housing options available
  • Standalone or Rack-Mount
  • Transparent extension of phone lines
  • SFP Based optics

Functional Characteristics:

The FXO modem is used for exchange (PBX or direct dial service from a telephone company) connected telephone lines. These units are designed to be used in conjunction with the FXS modem, which supply a subscriber (telephone handset) interface. When configured in this way, the modems provide a fiber optic link for regular, 2-wire analog telephones. Both FXO and FXS devices use SFP optic modules to achieve transmit distances of up to 20km over a single pair of fiber-optic cable.

Audio Transmission Characteristics:

The FXO accepts a telephone audio signal on its RJ11 connector from the exchange, and digitizes it with an analog-to-digital converter. Each of the digital samples is then encoded and applied to the SFP for transmission over the fiber optic cable. The remote FXS unit decodes the signal from the SFP module and applies it to digital-to-analog converter to recover the analog audio. The converse occurs in the other direction for the FXO. The telephone modem transmits analog signals of 300 to 3400Hz.

RS-485 / RS-422 Transmission Characteristics:

The FXO and FXS tele-data modems accept balanced RS-485/RS-422 data on the RJ45 connector for transmission across the fiber optic line. Data speeds of up to 64kbps are achievable. This interface is full duplex only.

Physical Characteristics:

The telephone modems themselves measure 7.0” wide x 0.84” high x 11.6” deep and are designed to be mounted in a variety of VERSITRON enclosures and chassis. The “Desktop” option is a single-card enclosure (model HF-1). Rack-mount options include a 2-Slot 19” standard rack-mountable chassis (model HF-2SS). For either of these installation options, each modem requires a wall transformer (model PSAC20) included with each kit. The one-pin power connector for electrical input is on the back of FXO and FXS cards. There is an RJ11 jack for the telephone line on the front of the cards. There is an SFP module slot on the back of the cards for the SFP fiber optic interface.

Dimensions of Enclosures & Chassis:

Model #



Power Supply


1.3 x 7.1 x 11.6 inches
(H x W x D)

Single Card Desktop Enclosure



1.7 x 19.0 x 13.8 inches
(H x W x D)

Dual Card Rack-Mount Chassis (side-by-side)


For more information regarding our 4-channel phone kits, please contact us directly. We stand ready to help you with your project!