thanks for the information but that seems to be what the consis is when it
comes to the oregin of this term. I figured it had to do with telephone
or something like that.
On Tue, 20 Mar 2001, Martin McCormick wrote:
> The term trunking comes from the telephone system and is
> an old and long-established concept.
>
> When you use a telephone to call from one place to
> another such as calling from work to some other business or
> calling from your house to talk to somebody in another town, your
> call may start out on a pair of wires that ends up at your house
> and only your house, but much of the equipment that carries your
> voice is equipment that you more or less borrow for the duration
> of the call. There is the dial tone that the switch sends to you
> which is one of only a relatively few dial tone generators
> available, the idea being that most people do not stay on the
> dial tone for very long.
>
> Then you actuate the switch which, in most places these
> days is a large special-purpose computer. While you are dialing,
> you tie up other special equipment that is listening to your
> tones or counting the pulses until you dial enough digits to make
> a valid phone number.
>
> At that point, you seize what is called a trunk line
> which in this day and age is probably one channel of a fiber
> optic cable that may be carrying thousands of other calls. It is
> a trunk because it is like a tree trunk. It supports all other
> parts of the tree.
>
> Now for radio, the exact concept is used on trunking
> systems. Rather than each department in a city, for example,
> having its own frequency that may only be used for a few minutes
> each day, every single department from the police and fire
> departments to code enforcement or Animal Control is on a complex
> system that keeps a running map of who is using what frequency.
> A system like Tulsa, Oklahoma's trunking system has twenty trunks
> or channels, each one of which can carry traffic from any of the
> city departments.
>
> A master controller acts like the telephone switch in
> your neighborhood and sends out that real-time map to every city
> radio that isn't actually talking to somebody. The fire fighters
> only hear fire traffic and the garbage trucks can only talk to
> other garbage trucks, but the trunking system keeps it all
> straight just like telephone trunks have done for years.
>
> It is the most efficient way to use resources. I have no
> idea how many separate frequencies Tulsa used to have, but every
> single department from the school system to the electric utility
> for Tulsa had its own fleet of radios on one or more channels so
> I bet it was probably upwards of 100 channels.
>
> The telephone company uses trunks for the same reason.
> There just isn't enough room to run a pair of wires from your
> house to everywhere you might want to call so trunk lines are
> used and reused thousands of times a day to make the system
> manageable.
>
> Just as another example, Oklahoma State University
> supports nearly 20,000 students and another roughly 3,000 staff
> and faculty. There are only 150 trunk lines leading from campus
> to the outside telephone network and it is seldom that they are
> ever all full.
>
> Martin McCormick WB5AGZ Stillwater, OK
> OSU Center for Computing and Information Services Data Communications Group
>
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