WISCO International

Home Page | Products | Manufacturers | Zetron | Quotation | Search | E-mail




When telephone service must be brought to a building that�s offshore, in the mountains, or in other remote locations, it can be prohibitively expensive to run wire lines.
A full-duplex radio link can often span the distance for a fraction of the cost of phone wires; however, you can�t just connect phone wires to a radio transmitter�s input - they are totally incompatible.

The Zetron Model 72 Extend-a-Line takes care of the telephone line to radio link problem. Ringing, DTMF, and rotary dialing, phone battery, dial and busy tones, and the conversation all pass cleanly through the radio link. The user answers and places phone calls like an ordinary phone call, without any special procedures or understanding.


The Zetron Model 72 Extend-a-Line makes it easier than ever to deliver telephone service to nearly any remote location. Rural telephony, emergency service, and PSTN access from remote radio sites are all perfect applications for the Model 72. Provide your remote customers with a high performance telephone circuit using a pair of full duplex radios and the Model 72 Extend-a-Line.


Resellers will appreciate the ease with which they can configure and sell low density rural telephone systems. System operators with remote radio sites lacking telephone lines will find the Model 72 is the perfect means of extending the reach of the telephone network, and will appreciate the high quality audio. Extend-a-Line offers wide area telephone service without the requirement for expensive, foreign exchange (FX) telephone lines.
Rural telephone companies can provide service to potential customers where wired service would be too expensive or simply impossible. Telephone companies will appreciate the Model 72�s low cost and simple radio interface, making the difficult task of providing emergency services much easier.


Single Line Extension
Where single line extension is required, the operation of the Model 72 is completely transparent to the users. When the �remote� user picks up the phone they will hear dial tone; when a call is received the �remote� telephone rings and is processed just like a normal call.

Multiple Remote Phones, Single CO Phone Line
An application may require remote telephones at multiple sites to access a common phone line. In this mode, up to ten remote phone locations may operate in a �party line� fashion. If a remote user picks up the phone when the channel is in use, they will hear a busy tone. Pressing the key and hanging up will cause the phone to �triple ring� when the channel becomes available.
For calls to the remote telephones, a selection digit is required from the phone caller. When a user dials the
Model 72 CO Base, it will answer the call then issue a dial tone prompt. The caller will then overdial a digit to select which remote telephone to ring. An optional dial click detector may be installed in the Model 72 CO Base to allow compatibility with callers using rotary dial phones.

Multiple CO Phone Lines, Single Remote
The Model 72 can support applications where a remote location needs to access more than one CO phone line. In this mode the remote telephone caller will need to select the phone line with a single prefix digit. The Model 72 will issue dial tone prompting the caller to select a line. Calls to the remote telephone from any of the CO phone lines function just like a normal call.

Extend DID Lines to a Remote Paging Terminal
A Direct Inward Dial (DID) version of the Model 72 is designed to extend a trunk level access line. A typical
application is extending a DID line to a remote paging terminal, or transporting DID service from a distant area to wherever the paging terminal is located.
Multiple Model 72 DID CO base units may share a common DID remote unit connected to a single line DID terminal, and thus extend DID service from multiple cities into a common remote paging terminal.


  • Uses radio to extend telephone lines to remote locations
  • Easy interface to any full duplex capable radio
  • Compander and high performance hybrid provide �wired� audio quality
  • Compatible with tone and pulse telephones
  • Works with FAX machines and modems
  • A single Extend-a-Line CO base may call up to ten remotes
  • A single Extend-a-Line remote may call up to ten base units
  • Ideal for emergency telephone service and rural telephone applications
  • Busy channel lockout and Morse code ID
  • Field configurable
  • DID version available for extending a trunk line to a remote paging terminal
  • Dial click decode option for rotary overdial




Power 11 - 16 VDC ~ 750 mA
Temperature 0 to 65 degrees Celsius
Size 19" W x 6.25" D x 1.4" H
Weight 2.0 pounds


Line type End-to-end (B1) telephone line
Connector RJ11-C modular jack
FCC Registration EYB USA-74165-OT-E
Incoming call Ring detection on tip-ring pair
Call answer Off-hook, tip-ring current draw
Call disconnect Channel busy, remote hang up, or call limit timer expiration


Line type DID immediate dial or wink start
Connector RJ11-C modular jack
FCC Registration EYB USA-74165-OT-E
Incoming call Loop start
Number of feed digits 2, 3 or 4, pulse or DTMF
DID Battery Supply 48V DC, current limited at 60 mA
Unsupervised: Tip + Ring -
Supervised: Tip - Ring +
Disconnect Loss of loop current > 350 mS


PTT Relay with normally open and normally closed contacts
RX Carrier detect Internal RX noise detector
TX Audio -40 to +6 dBm. Hi/Lo range selection 1K Ohm output impedance
RX Audio -40 to +10 dBm. Hi/Lo ange selection, 50K Ohm input impedance, for connection to RX discriminator audio


Indicators Power, Ring, Off-Hook, Carrier, Transmit, DTMF, Signaling
Station ID Morse code, fixed 1200 Hz frequency, programmable ID sequence (not available in the DID version)
User prompt tones Call progress tones, error tones, and warning tones to signal user errors and link failure
Secondary protection Telephone line input is protected with high voltage clamps with protective fusing elements
WISCO International, Inc. - MIAMI, FL U.S.A.
Fax: (954) 370-3997 | E-mail: wiscointl@wiscointl.com

Home Page | Products | Manufacturers | Zetron | Quotation | Search | E-mail