Backcountry Phones

by Equant

There are a few reasons for this article.

First, several years ago while cruising around New Mexico with a good friend we ran across a radiotelephone.  It was in a park, and I've always assumed it was for park rangers to use.  We horsed around with it and didn't accomplish much.  Had we been prepared for what we found we might have been more successful.

Another reason for this article is that radiotelephones are common outside of the United States, and I've always enjoyed 2600's drive to inform everyone around the world.

The last reason is I've never seen much said about radiotelephones.  So read the following, and if you run into a radiotelephone in the woods you'll know it's not a complex weather station.

Radiotelephones are used to connect isolated areas to a phone network without the installation of phone lines.  Some places you might find a radiotelephone would be in remote industrial parks, islands, and isolated communities such as state militia headquarters, cult compounds, and communes.

There are a few different types of radiotelephones.  It seems that OptaPhones and Ultraphones are the most popular.  Radiophones usually operate somewhere between 30 MHz and 3000 MHz.  All users of radiotelephones (in the U.S.) need FCC licenses (hooray for the FCC!).  They are all full-duplex and can use standard phone equipment on the subscriber's end (i.e., the subscriber gets an RJ11 jack to plug a normal phone into, or a modem or a fax).  I've not heard of a radiotelephone that can transmit data over 9600 bps.

OptaPhones

These systems are for individuals or small groups of people.

First we need to travel from the telco's switch along a phone line to the middle of nowhere.  Once the line ends we'll find a base unit.  The base unit has a power supply (perhaps a battery and a solar panel), a phone box, and a Yagi antenna.  The Yagi antenna of course is pointed at the subscriber's Yagi antenna which is connected to their box which is connected to their phone.

There is an OptaPhone called the Community OptaPhone STAR which is a similar setup to the above, with the two Yagi antennas, but you have a more complex subscriber box which can operate 24 trunks at once.  With this system you can have 96 subscribers.

Keep a look out for this system in Alaska, Montana, and Pennsylvania.

Ultraphones

Ultraphones are mostly purchased by telcos.  They are not one subscriber systems like the OptaPhone.  The Ultraphones support true digital local loop service and can handle 896 lines and 95 full-duplex trunks.

Like the OptaPhone it has two components, the subscriber side and the host side.  The host's end has two parts.

In the telco's central office is the Central Office Terminal (COT).  The COT is a PBX with a voice-frequency loop level connection to the central office.  From the COT the signal is sent to the Radio Carrier Station which sends the signal up a large radio tower.  (Note this is an omni-directional antenna and not a Yagi antenna.)  The signal is not line of site, and can reliably go 37.5 miles (60 km).

On the subscriber's end you have a Yagi antenna connected to a radio modem and power supply.  The subscriber unit can handle normal RJ11 phone equipment, with DTMF and pulse-dialing.  The subscriber broadcasts somewhere from 454.025 MHz to 454.650 MHz and receives between 459.025 MHz and 459.605 MHz.  Each channel is separated by 25 kHz, and each channel can contain four trunks.

The signal goes from the subscriber's mouth into the subscriber's phone.  The analog signal is then converted into a 14.57 kb/s digital signal.  The signal is modulated and transmitted at a rate of 64 kb/s.  This signal is multiplexed with three other signals in order to obtain the four trunks per channel.

Locations in the U.S.

There are 120 systems in the U.S.  Most of them are west of the Mississippi River.  I'm not sure of all the locations, but here's what I do know.

There is at least one system in Florida, Maine, California, and New Mexico.  There are two in Arizona, one on the Navajo reservation.  GTE in Texas has 30 systems.

The most interesting is that Big Bend Telco, southeast of El Paso, serves two thirds of its exchanges (25,000 square miles) with 15 systems.

Locations Outside the U.S.

Worldwide there are over 300 Ultraphone systems.

Here's a list:

Indonesia 46 Mexico 39 Philippines 26 Myanmar 7 Puerto Rico 5 Russia 5 Brazil 4 Columbia 4 Canada 3 Sri Lanka 3 Haiti 2 Korea 2 China 1 Kuwait 1 Nigeria 1 Taiwan 1 Venezuela 1