* In a message to Steve Brack on 10-01-97, CHARLES HUNTER said the following:
CH> SB>        Owing to a generational difference 8-), I've never seen an
CH>   >        IMTS phone in operation.  Could one of the more experienced
CH>   >        participants fill me in on how the system worked?  I think I
CH>   >        saw it on "Perry Mason" on TV once, but I'm not sure.
CH> 
CH> Improved Mobile Telephone Service (IMTS) operated primarily on the
CH> 150 MHZ band (Similar in 450 MHz).  Basically the mobile unit consisted 
CH> of a trunk mounted transceiver with a telephone style head with (I 
CH> believe) 11 channels. (e.g. YP, JP, etc.).  The control heads initially 
CH> had rotary dials and used pulse dialing; but were replaced by touch 
CH> tone pads.  They were great units.  Because of the VHF frequency, I 
CH> could get on top of a mountain 40 or 50 miles away from my home area 
CH> and get into my home service area avoiding toll charges and roaming 
CH> charges.  (Don't remember for sure if there were roaming charges).  The 
CH> two best IMTS phones that I remember were the Motorola and the RF 
CH> Communications (later known as Harris).  The transmitter packs, as I 
CH> remember transmitted at 25 or 50 watts of power.  The automation in the
CH> system consisted of the unit scanning for available IMTS frequencies to 
CH> make a call; and with the base stations sending out a call by scanning
CH> channels to find one your unit was on.
        Thanks, Charles.  That's a bit different from the system I saw
        on TV, which relied on an operator to get your number for you.
        I'm guessing it was an earlier version of the same system.
        Your explanation does raise a couple of questions for me.  How
        did individual units identify themselves to the "system" for
        billing purposes, and how did individual phones know when it
        was them being called?  I know how cellphones do it, but I
        don't see how a system lacking a "control channel" could.
 -- SPEED 2.00 #2712: Missed me by THAT much -- Maxwell Smart
--- GEcho 1.00
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