|
|
Notes:
- Base stations (also called cell sites) are connected to an MTSO
- MTSO (Mobile Telephone Switching Office) is also known as MSC (Mobile Switching Center)
- Average base station covers 5 to 10 miles
- Maximum mobile power output is 3 watts
|
|
History
System Diagram
Frequency Allocations
Frequency Allocations
Cellular Security
Cellular Telephone Programming
Monitoring Data Streams
Return to Decode Systems home
|
Mobile radiotelephone service began in St. Louis on June 17, 1947.
Click here for more information, straight from Bell Telephone, about their mobile service in 1954.
Commercial cellular service began in the United States in October, 1983.
By the end of 1984 there were about 40,000 cellular customers.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Notes:
| Mobile Transmit | Base Transmit | Channel |
Use |
Band |
| 824.04 - 825.00 | 869.04 - 870.00 | 991 - 1023 | Voice | A |
| 825.03 - 834.36 | 870.03 - 879.36 | 1 - 312 | Voice | A |
| 834.39 - 834.99 | 879.39 - 879.99 | 313 - 334 | Control | A |
| 835.02 - 835.62 | 880.02 - 880.62 | 335 - 356 | Control | B |
| 835.65 - 844.98 | 880.65 - 889.98 | 357 - 666 | Voice | B |
| 845.01 - 846.48 | 890.01 - 891.48 | 667 - 716 | Voice | A |
| 846.51 - 848.97 | 891.51 - 893.97 | 717 - 799 | Voice | B |
Notes:
|
|
Notes:
Despite the best efforts of the
Cellular Telephone Industry Association,
it has become clear to almost everyone that there is no privacy and
little security with traditional analog calls.
Migration to digital systems was supposed to give callers a "secure"
capability, but such has not been the case. Based on a lot of
hints from a very smart Australian, in March of 1997 a
group of cryptographers announced they had broken one of three
encryption systems used in one of the new digital systems. Read
their announcement here.
This Candian website
streams Ottawa-area analog cell phone conversations over the Internet
to prove the point that these calls are in no way private.
Cellular telephones store their operating parameters in a device
known as a Numeric Assignment Module (NAM). Most modern phones
allow the NAM to be changed via the keypad after entering a
"secret" sequence.
Sequences for a number of popular phones used to be available at the
Radiophone Archive, however
that site appears to be down.
Cellular control channels contain data concerning the system
itself and calls that may be taking place on the network.
For law enforcement personnel and cellular industry technicians,
equipment is available for monitoring those channels.
Custom Computer Services
offers a number of products catering to the data monitoring and
locating crowd.
Electronic Countermeasures Inc.
is a Canadian company offering, among other things, "Cellular and
Paging Analysis Systems."
For the do-it-yourselfer, cellular data stream monitoring will require
a scanner capable of tuning the 800 MHz band and access to the
FM discriminator. Bill Cheek (RIP) wrote useful
guide to accessing the discriminator
on various receivers to extract unfiltered audio, which helps
immensely in decoding data signals.