* In a message to Steve Brack on 10-06-97, SCOTT CHRISTENSEN said the 
llowin
SC> I'm not sure how the old "operator required" system did it (I arrived on 

SC> scene too late for that) - but the IMTS radios had a "control" board 
here
SC> programmed the unit (phone) number by soldering in diodes to a matrix.  
h
SC> radio would send this number to the switch when it went off hook and 
ould
SC> respond to rings on that number.  If it hadn't been addressed, the radio
SC> remained "squelched" so it couldn't hear other traffic on the system.  
nd
SC> besides - it scanned to look for the idle tone on one channel of the 
yste
SC> (I don't recall how many channels the radios could support - but I do 
eca
SC> it was at least 4 and that the radios required expensive "channel 
lements
SC> (crystals and oscillators) for transmit and receive.)
        Pretty interesting system.  Change your phone number with a
        soldering iron.  8-)  I imagine that was an expensive system
        to have installed and to use.  Do you know whether there are
        any IMTS installations still up & running in the U.S.?
SC> These high powered (250W on the base!) VHF and UHF phone systems were a 
a
SC> cause of intermod in those bands.  (Just imagine the problems caused by a
SC> number of evenly spaced high power transmitters...)  Good riddance!  
here
SC> now fewer things to listen to on the scanner, but what is there is 
leaner
SC> (The recent laws would have prohibited listening to these channels 
nyway.
SC> It's a good thing these channels were no longer used by phones when the 
a
SC> were enacted, or there would be holes in our VHF and UHF coverage too!)
        With the new laws prohibiting listening to telephone calls
        whether cellular or not, is it now illegal to listen to VHF
        marine channels when phone patches are happening, or to 800MHz
        public service bands when they're using a channel or two for
        phone patches?  Of course, with the new anti-scanner law
        working its way through Congress, it may become a moot point.
 -- SPEED 2.00 #2712: Math & alcohol don't mix; Please don't drink and derive
--- GEcho 1.00
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