306 lines
16 KiB
Plaintext
306 lines
16 KiB
Plaintext
=======================================
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[ Hacker Supreme - Hack Directory #19 ]
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=======================================
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(info Uploaded to The Cartel AE Line.)
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Mobile Telephone Communications
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Mobile telephone communications is not the same thing as Cellular. Mobile
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telephone service is not as advanced as Cellular, and not as efficient. Mobile
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telephone service limits the number of customers sharply, while Cellular is
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designed to solve the problems of Mobile telephone service.
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The signals for Mobile communications are sent by high-power transmitters and
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antennas that provide an area of approx. 20-30 miles with service.
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A base unit of a Mobile communications system transmits and receives on
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different frequencies at the same time. Typical power for the radio base
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station transmitter is 200-250 watts.
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Mobile telephone facilities tie in with the normal fixed-position telephone
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system, however base units can be owned by a Radio Common Carrier (RCC). RCCs
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running mobile telephone systems are charged by the telephone company for use
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of the normal phone system.
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DIAGRAM:
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--------
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^-Base antenna Mobile unit
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|- - - - - - - - - /-- --\
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| ^Signal^ | (Car) |
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---------------------------------------
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^-------<-20-30 Miles->---|
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^ |-From
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/===========\ | mobile
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|Receiver/ | | antenna
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|Transmitter| =============
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/===========\ |Receiver/ | |-|
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|Control | |Transmitter|-|*|
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|Terminal | ============= |-|
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\===========/ ^
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| Handset
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| <-Telephone
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| <-Land line
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======= =======
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| C.O.| | C.O.|---[-*-]
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======= ======= |*|
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| | -----
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| | Fixed
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========= ========= Phone
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|Switch |--------------|Switch |
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|Network| Transmission |Network|
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========= Link =========
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---------------------------------------
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(Above diagram from 'Understanding Telephone Electronics' chapter 10.)
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As you can see from the above diagram, calls placed from the Fixed position
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telephone are routed through a Central Office as normal, through a Switch
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Network, to another Switch network, and to another CO. From the second CO
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(nearest to the Mobile unit), the signals are sent on a telephone line to the
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control terminal, to the receiver, then to the base unit (antenna). From the
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base unit, the radio signals are sent to the site of the mobile telephone.
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Calls from the mobile telephone operate in the same manner. An idle radio
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channel is selected (like seizure of a trunk for a LD call) and the signals are
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sent over the mobile network.
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If no channel is available for use, then a busy indication is triggered
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(similar to a re-order). If a channel is available, the customer will be
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prompted with a dial tone, similar to normal fixed-position telephone service.
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The area that this would work in is called the subscriber's home area. When a
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mobile telephone service subscriber leaves the service area, he is then
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referred to as a Roamer. Since the mobile unit is out of the service area,
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special preparations have to be made to continue communications to/from that
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mobile unit.
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SIGNALLING
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----------
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Mobile signalling tones are selected (like touch tones) to avoid possible
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reproduction of the signalling tone on the voice link, to cause a signalling
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mistake. The IMTS (Improved Mobile Telephone Service) uses in band signalling
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of tones from 1300Hz-2200Hz. Another method of signalling is the MTS (Mobile
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Telephone System). MTS is older than IMTS, and MTS uses in band signalling of
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tones from 600Hz-1500Hz, and some use 2805 Hz in manual operation.
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CALL COMPLETION
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---------------
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In this instance, let's say a call is being placed from a normal telephone to
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a Mobile unit. First off, the base station selects one idle channel and places
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a 2000Hz idle tone on it. All on hook Mobile units active in that service area
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find and lock onto the channel that carries the 2000Hz idle tone. Now each
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Mobile unit listens for it's specific number on that channel. When an idle
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channel becomes busy, a new channel is selected for use, and the process is
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repeated.
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Now the caller's call is sent through the telephone network the same way as a
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normal telephone call. When this call reaches the control terminal, the
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terminal seizes the already marked idle channel (with every on-hook mobile unit
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listening to it) and applies a 1800Hz seize tone. This tone keeps other mobile
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units from using it to complete other calls. The called number is outpulsed
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over the base station transmitter at ten pulses per second, with idle tone
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represented as a mark, and a seize-tone represented as a space.
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Since every idle mobile unit is waiting on that channel, they compare the
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number being outpulsed with their own number. If the first digit of the called
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mobile unit is three, and a specific mobile unit 'listening' on the channel has
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a first digit of four, it stops listening to that channel, and moves to the
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next channel with 2000Hz applied.
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When the mobile unit receives the correct destination number, all other
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mobile units are no longer listening on that particular channel. When the 7
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digit number is received, the mobile supervisory unit turns on the mobile
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transmitter and sends an acknowledgement signal (2150Hz guard tone) back to the
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control terminal. If this signal isn't received in three seconds after
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outpulsing, the seize tone is removed from that channel, and the call is
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dropped. If the signal is received at the control terminal, then the mobile
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phone will ring (standard two seconds on, four seconds off). If the mobile unit
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being called doesn't answer in forty five seconds, the call is also dropped.
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When the person answers the mobile phone and takes it off hook, the mobile
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supervisory unit sends a connect tone of 1633Hz, for an answer signal. When
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this is received by the control terminal, the ringing stops, and a voice path
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between the two phones is established. When the mobile subscriber hangs up, a
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disconnect signal is sent which consists of alternating disconnect/guard tone
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(1336Hz and 2150Hz respectively) signals. Then the mobile unit begins searching
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for another idle channel, and readies itself for more calls.
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For an outgoing call placed by the Mobile subscriber, the mobile unit must
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already be locked on the idle channel. If the unit is not, a warning light will
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flash advising the user of the problem. This is similar to a re-order signal.
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If the unit is already on an idle channel, the calling number will be sent to
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the control terminal for billing purposes.
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CELLULAR TELEPHONES
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-------------------
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To improve over the problems of mobile telephone service such as low amount of
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users, high price, etc. AT&T invented the Cellular Concept, or the AMPS
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(Advanced Mobile Phone System). This is the cellular phone concept that is used
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in major cities. Los Angeles, Ca. currently has the largest cellular
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communication system in the world.
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Calls sent to cellular telephones are sent through the MTSO (Mobile
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Telecommunications Switching Office). The MTSO handles all calls to and from
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cellular telephones, and handles billing.
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All incoming calls from the MTSO are sent to a Cell site in each cell, to the
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actual cellular telephone. The major difference between mobile and cellular is
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that cellular can use the same channel many more times than a mobile telephone
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system can, providing more customers and making the service less expensive.
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Once a vehicle goes out of range of one cell site, the signal is transferred
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immediately, with no signal loss, to another cell site, where the call is
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continued without interruption. This is called a Cellular hand-off.
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Cellular communications areas are divided up into several cells, like a
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honeycomb.
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DIAGRAM
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-------
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/---\ /---\ /---\ / * \/ * \/ * \
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==== |Cell ||Cell ||Cell |
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|CO| | Site|| Site|| Site |
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==== /---\\ /\ /\ /
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| / * \\---/ \---/ \---/
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| |Cell | /---\ /---\
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| | Site|/ * \/ * \
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| \ /|Cell ||Cell |
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====== \---/ | Site|| Site |
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|MTSO| \ /\ /
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====== \---/ \---/
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---------------------------------------
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More cell sites are used for the area they are needed for. The signals are
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sent from the MTSO to the each cell site. So if you were travelling in the cell
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site to the far left, the signal from the MTSO would be sent to that cell. As
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you move, the signal is moved.
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Here is a quote from AT&T's Cellular Telephones pamphlet.
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'AT&T cellular phone transmission sounds as good as your home and office
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phone. Basically it's a simple concept. Each metropolitan area is divided into
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sectors which form a honeycomb of cells. Each cell incorporates its own
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transmitter and receiver which connects to the local phone network.
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As you drive from cell to cell, sophisticated electronic equipment transfers
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or 'hands off' the call to another cell site. This automatic sequence maintains
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service quality throughout the conversation without interruption.'
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I hope this file has been of some assistance to anyone who is curious about
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the more technical aspects of the telephone system.
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References
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Understanding Telephone Electronics-by Texas Instruments 1983
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TELE Magazine issues three and four
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AT&T Mobile communications pamphlet
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AT&T Cellular concept pamphlet
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CENTREX/CENTRON CALL FORWARDING (CONTINUED FROM TSR ISSUE #1)
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IN THE FIRST ARTICLE ON CENTREX/CENTRON CALL FORWARDING, I STATED I
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WOULD LIST A FEW ALTERNATE ACCESS CODES IN THE 5 STATE AREA. IF YOU NEED
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THE ALTERNATE ACCESS CODES IN YOUR AREA, TRY TO CONTACT ME ON MOST ASCII
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EXPRESS LINES.
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ALTERNATE
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LOCATION CENTREX/CENTRON ACCESS CODE
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-------------------------- -----------
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IOWA SIOUX CITY (712-279) 8
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COUNCIL BLUFFS (712-328) 8
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DES DOINES-NORTHWEST (515-270,278) 8
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"" "" -DWTN. (515-286) 110
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"" "" -ASHWORTH (515-223) 8
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"" "" -EAST (515-263) 111
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WATERERLOO (319-291) 8
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DAVENPORT 319-383) 8
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CEDAR RAPIDS (319-399) 8
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MINNESOTA
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MPLS.-DWTH. (612-344) 101
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PLYMOUTH (612-536) 101
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GOLDEN VALLEY (612-542) 111
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BLOOMINGTON (612-887) 101
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ST. PAUL-MIDWAY 111
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NEW BRIGHTON (612-631) *19
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ST. PAUL-SHOREVIEW (612-482) 101
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ST. PAUL-DWTN. (612-221) 111
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ST. CLOUD (612-255) 101
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ROCHESTER (507-285) 111
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BRAINERD (218-828) 111
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NEBRASKA
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OMAHA-DWTN. (402-422) 101
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OMAHA-IZARD (402-554) 101
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OMAHA-FORT (402-496) 101
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GRAND ISLAND (308-381) 8
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NORTH DAKOTA
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FARGO (701-247) 8
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BISMARK (701-222) 8
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SOUTH DAKOTA
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RAPID CITY (605-394) 115
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ABERDEEN (605-622) 115
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SIOUX FALLS (605-339) 115
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TWO ADDITIONAL LOCATIONS ARE SCHEDULED FOR CONVERSION TO CENTRON
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SERVICE SOON AND WILL BE REQUIRED TO USE THE ALTERNATE ACCESS CODE FOR CALL
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FORWARDING AT THAT TIME.
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IOWA DUBUQUE (319-588) 8 DUE LATE JUNE'86
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NEBRASKA NORFOLK (402-644) 8 DUE MID JULY'86
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===========================================================================
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COMPETITIVE PHONE COMPANYS REACT:
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MCI AND GTE SPRINT ANNOUNCED PLANS TO REDUCE THEIR LD RATES EFFECTIVE
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JUNE 1. THE TWO COMPANIES SAID THEIR RATES WOULD BE COMPETITIVE WITH AT&T,
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WHICH HAD BEEN EARLIER ANNOUNCED IN TSR ISSUE #1 OF THE RATE CUT ALSO
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EFFECTIVE JUNE 1. INCLUDING 11.4 PERCENT FOR DAY AND EVENING HOURS AND MANY
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OTHER SIMILAR REDUCTION.
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===========================================================================
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NWB'S INTRO TO 'SMART PHONES':
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NORTHWESTERN BELL'S PUBLIC SERVICES LINE OF BUSINESS IS FIELD
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TRIALING A NEW COIN PHONE PRODUCT - ONE IT HAD A HAND IN CREATING. THE NEW
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COIN PHONE PRODUCT IS THE NBT(TM) 1062 COIN PHONE RETROFIT KIT DESIGNED BY
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NWBELL TECHNOLOGIES. THE KIT CONVERTS STANDARD PUBLIC COIN PHONES -
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DEPENDENT ON CENTRAL OFFICE ELECTRONICS - INTO "STAND ALONE" COIN PHONES,
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WHICH HAS BEEN LABELED BY CODENAME AS "SMART PHONES." THERE ARE MANY NEW
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FEATURES OF WHICH CUSTOMERS WILL NOT NOTICE. ALTHOUGH THE ONLY NOTICEABLE
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CHANGE BETWEEN THE RETROFITED COIN PHONES AND THE RADITIONAL PUBLIC COIN
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PHONES IS THE VOICE IN THE RETROFITED MODE, GENERATED BY THE KIT'S ELECTRONIC
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CIRCUIT BOARD. IT INSTRUCTS USER TO DEPOSIT MONEY. CURRENTLY THE SMART
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PHONES ARE BEING TESTED IN 40 COIN PHONES AROUND THE NORTHWESTERN BELL.
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===========================================================================
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LOCAL AREA NETWORKS (LAN):
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A LOCAL AREA NETWORK IS A SYSTEM OF HARDWARE AND SOFTWARE THAT
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CONNECTS A VARIETY OF SIMILAR AND DISSIMILAR COMMUNICATIONS DEVICES. THESE
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DEVICES TYPICALLY ARE OPERATED BY A SINGLE COMPANY FOR INTERNAL USE WITHIN A
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LIMITED GEOGRAPHICAL AREA. THE SYSTEM ALLOWS HIGH SPEED COMMUNICATIONS
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BETWEEN DEVICES ON THE NETWORK WHILE MAINTAINING DATA SECURITY, BELL SO
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BOLDLY CLAIMS. A VARIETY OF TRANSMISSION MEDIA ARE AVAILABLE IN THE LAN
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MARKETPLACE. THESE CATEGORIZE THE MAJOR TYPES OF LOCAL AREA NETWORKS IN USE
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PRESENTLY. THE MOST PREVALENT ARE TWISTED PAIR (COPPER) AND FIBER OPTIC
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CABLE. BECAUSE OF ITS SUPERIOR TRANSMISSION CAPABILITIES, FIBER IS CONSIDERED
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TO BE THE MEDIA OF CHOICE FOR THE FORESEEABLE FUTURE WITHIN BELL.
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===========================================================================
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-----------------------------------------------------------------------------
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Another Great Directory from Hacker Supreme.
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(Ninja Squirrel /+\, Logan - 5, Zaphod Breeblebox, Silicon Rat, Lord Vision.)
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-----------------------------------------------------------------------------
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==============================================================================
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[ Infinity-Cartel Network ]
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[ The Cartel Adventure/AE/Hack BBS 5.5 meg --- 206-825-6236, or 206-939-6162 ]
|
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[ Infinity's Edge Adventure/AE/Cat/Hack 10 meg BBS ------------ 805-683-2725 ]
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==============================================================================
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]
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[ The Cartel Adventure/AE/Hack BBS 5.5 meg --- 206-825-6236, or 206-939-6162 ]
|
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[ Infinity's Edge Adventure/AE/Cat/Hack 10 meg BBS ------------ 805-683-2725 ]
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================= |