Advanced Mobile Phone System
Advanced Mobile Phone System (AMPS) is an analog mobile phone system
standard developed by Bell Labs, and officially introduced in the
Americas on October 13, 1983,
Israel in 1986,
Singapore in 1988, and
Pakistan in 1990. It was the primary
analog mobile phone system in
North America (and other locales)
through the 1980s and into the 2000s. As of February 18, 2008,
carriers in the United States were no longer required to support AMPS
and companies such as AT&T and Verizon have discontinued this
service permanently. AMPS was discontinued in
Australia in September
Pakistan by October 2004, and Brazil by 2010.
6 Digital AMPS
7 Successor technologies
8 Analog AMPS being replaced by digital
9 Companies that used analog AMPS
10 See also
Main article: History of mobile phones
The first cellular network efforts began at
Bell Labs and with
research conducted at Motorola. In 1960, John F. Mitchell, an
electrical engineer who had graduated from the Illinois Institute of
Technology, became Motorola's chief engineer for its
mobile-communication products. Mitchell oversaw the development and
marketing of the first pager to use transistors.
Motorola had long produced mobile telephones for automobiles, but
these large and heavy models consumed too much power to allow their
use without the automobile's engine running. Mitchell's team, which
included the gifted Dr. Martin Cooper, developed portable cellular
telephony, and Mitchell was among the
Motorola employees granted a
patent for this work in 1973. The first call on the prototype
connected, reportedly, to a wrong number.
Motorola was developing a cellular phone, from 1968-1983 Bell
Labs worked out a system called
Advanced Mobile Phone System
Advanced Mobile Phone System (AMPS),
which became the first cellular network standard in the United States.
The first system was successfully deployed in Chicago, Illinois, in
Motorola and others designed and built the cellular phones for
this and other cellular systems.
Martin Cooper, a former general manager for the systems division at
Motorola, led a team that produced the DynaTAC8000x, the first
commercially available cellular phone small enough to be easily
carried, and made the first phone call from it. He later introduced
the so-called Bag Phone.
In 1992 the first smartphone, called
IBM Simon, used AMPS. Frank
Canova led its design at
IBM and it was demonstrated that year at the
COMDEX computer-industry trade-show. A refined version of the product
was marketed to consumers in 1994 by
BellSouth under the name Simon
Personal Communicator. The Simon was the first device that can be
properly referred to as a "smartphone", even though that term was not
AMPS is a first-generation cellular technology that uses separate
frequencies, or "channels", for each conversation (see
frequency-division multiple access (FDMA)). It therefore required
considerable bandwidth for a large number of users. In general terms,
AMPS was very similar to the older "0G" Improved Mobile Telephone
Service, but used considerably more computing power in order to select
frequencies, hand off conversations to
PSTN lines, and handle billing
and call setup.
What really separated AMPS from older systems is the "back end" call
setup functionality. In AMPS, the cell centers could flexibly assign
channels to handsets based on signal strength, allowing the same
frequency to be re-used in various locations without interference.
This allowed a larger number of phones to be supported over a
geographical area. AMPS pioneers coined the term "cellular" because of
its use of small hexagonal "cells" within a system.
AMPS suffered from many weaknesses compared to today's digital
technologies. As an analog standard, it was susceptible to static and
noise, and there was no protection from 'eavesdropping' using a
In the 1990s an epidemic of "cloning" cost the cellular carriers
millions of dollars. An eavesdropper with specialized
equipment could intercept a handset's ESN (Electronic Serial Number)
and MDN or CTN (Mobile Directory Number or Cellular Telephone Number).
The Electronic Serial Number, a 12-digit number sent by the handset to
the cellular system for billing purposes, uniquely identified that
phone on the network. The system then allowed or disallowed calls and
or features based on its customer file. A person intercepting an
ESN/MDN pair could clone the combination onto a different phone and
use it in other areas for making calls without paying.
Dr. Martin Cooper of
Motorola made the first private handheld
mobile-phone call on a larger prototype model in 1973. (The image
shows a reenactment.)
Cellular phone cloning became possible with off-the-shelf technology
in the 1990s. Would-be cloners required three key items :
A radio receiver, such as the Icom PCR-1000, that could tune into the
Reverse Channel (the frequency on which AMPS phones transmit data to
A PC with a sound card and a software program called Banpaia
A phone that could easily be used for cloning, such as the Oki 900
The radio, when tuned to the proper frequency, would receive the
signal transmitted by the cell phone to be cloned, containing the
phone's ESN/MDN pair. This signal would feed into the sound-card
audio-input of the PC, and Banpaia would decode the ESN/MDN pair from
this signal and display it on the screen. The hacker could then copy
that data into the Oki 900 phone and reboot it, after which the phone
network could not distinguish the Oki from the original phone whose
signal had been received. This gave the cloner, through the Oki phone,
the ability to use the mobile-phone service of the legitimate
subscriber whose phone was cloned - just as if that phone had been
physically stolen, except that the subscriber retained his or her
phone, unaware that the phone had been cloned—at least until that
subscriber received his or her next bill.
The problem became so large that some carriers required the use of a
PIN before making calls. Eventually, the cellular companies initiated
a system called RF Fingerprinting, whereby it could determine subtle
differences in the signal of one phone from another and shut down some
cloned phones. Some legitimate customers had problems with this though
if they made certain changes to their own phone, such as replacing the
battery and/or antenna. The Oki 900, the ultimate tool of cell-phone
hackers, could listen in to AMPS phone-calls right out-of-the-box with
no hardware modifications.
AMPS was originally standardized by American National Standards
Institute (ANSI) as EIA/TIA/IS-3. EIA/TIA/IS-3 was superseded by
EIA/TIA-553 and TIA interim standard with digital technologies, the
cost of wireless service is so low that the problem of cloning has
AMPS cellular service operated in the 850
MHz Cellular band. For each
market area, the United States
Federal Communications Commission
Federal Communications Commission (FCC)
allowed two licensees (networks) known as "A" and "B" carriers. Each
carrier within a market used a specified "block" of frequencies
consisting of 21 control channels and 395 voice channels. Originally,
the B (wireline) side license was usually owned by the local phone
company, and the A (non-wireline) license was given to wireless
At the inception of cellular in 1983, the FCC had granted each carrier
within a market 333 channel pairs (666 channels total). By the late
1980s, the cellular industry's subscriber base had grown into the
millions across America and it became necessary to add channels for
additional capacity. In 1989, the FCC granted carriers an expansion
from the previous 666 channels to the final 832 (416 pairs per
carrier). The additional frequencies were from the band held in
reserve for future (inevitable) expansion. These frequencies were
immediately adjacent to the existing cellular band. These bands had
previously been allocated to UHF TV channels 70–83.
Each duplex channel was composed of 2 frequencies. 416 of these were
in the 824–849
MHz range for transmissions from mobile stations
to the base stations, paired with 416 frequencies in the
MHz range for transmissions from base stations to the
mobile stations. Each cell site used a different subset of these
channels than its neighbors to avoid interference. This significantly
reduced the number of channels available at each site in real-world
systems. Each AMPS channel had a one way bandwidth of 30 kHz, for
a total of 60 kHz for each duplex channel.
Laws were passed in the US which prohibited the FCC type acceptance
and sale of any receiver which could tune the frequency ranges
occupied by analog AMPS cellular services. Though the service is no
longer offered, these laws remain in force.
Later, many AMPS networks were partially converted to D-AMPS, often
referred to as TDMA (though TDMA is a generic term that applies to
many 2G cellular systems). D-AMPS, commercially deployed since
1993, was a digital, 2G standard used mainly by AT&T Mobility
U.S. Cellular in the United States,
Rogers Wireless in Canada,
Telcel in Mexico,
Telecom Italia Mobile
Telecom Italia Mobile (TIM) in Brazil,
Movilnet in Venezuela, and Cellcom in Israel. In most areas,
D-AMPS is no longer offered and has been replaced by more advanced
digital wireless networks.
D-AMPS have now been phased out in favor of either CDMA2000
or GSM, which allow for higher capacity data transfers for services
such as WAP,
Multimedia Messaging System
Multimedia Messaging System (MMS), and wireless Internet
access. There are some phones capable of supporting AMPS,
GSM all in one phone (using the GAIT standard).
Analog AMPS being replaced by digital
In 2002, the FCC decided to no longer require A and B carriers to
support AMPS service as of February 18, 2008. All AMPS carriers have
converted to a digital standard such as
CDMA2000 or GSM. Digital
technologies such as
CDMA2000 support multiple voice calls on
the same channel and offer enhanced features such as two-way text
messaging and data services.
Unlike in the United States, the Canadian Radio-television and
Telecommunications Commission (CRTC) and
Industry Canada have not set
any requirement for maintaining AMPS service in Canada. Rogers
Wireless has dismantled their AMPS (along with IS-136) network; the
networks were shut down May 31, 2007.
Bell Mobility and Telus
Mobility, who operated AMPS networks in Canada, announced that they
would observe the same timetable as outlined by the FCC in the United
States, and as a result would not begin to dismantle their AMPS
networks until after February 2008.
OnStar relied heavily on North American AMPS service for its
subscribers because, when the system was developed, AMPS offered the
most comprehensive wireless coverage in the US. In 2006, ADT asked the
FCC to extend the AMPS deadline due to many of their alarm systems
still using analog technology to communicate with the control
centers. Cellular companies who own an A or B license (such as
Verizon and Alltel) were required to provide analog service until
February 18, 2008. After that point, however, most cellular companies
were eager to shut down AMPS and use the remaining channels for
OnStar transitioned to digital service with the help
of data transport technology developed by Airbiquity, but warned
customers who could not be upgraded to digital service that their
service would permanently expire on January 1, 2008.
Companies that used analog AMPS
Verizon Wireless—Formerly operating an AMPS network, on February 18,
2008, Verizon has discontinued all AMPS service. Now primarily
Bell Mobility and
Telus Mobility operated AMPS networks in Canada,
though they have since been overlaid with digital services. Both Bell
Telus Mobility had announced that they would observe the
same shutdown guidelines as in the United States, and decommissioned
their AMPS networks in 2008.
Alltel—In 2005 disclosed that only 15% of their total customer base
are still using the existing analog network. The company has posted a
three phase turn down schedule, which was completed in September
2008. With the acquisition of Western Wireless,
Alltel now took the
claim of the "largest network in America." The claim was true, oddly
enough because of wide analog coverage in rural areas. All
D-AMPS service was discontinued in September 2008
Coastel Offshore Cellular—Operated an AMPS network in the Gulf of
Mexico that stretched from south of Corpus Christi, TX to south of
Gulf Shores, AL. In 2006 Coastel was the only carrier in the US whose
entire customer base was still 100% analog based. In 2007 Coastel was
merged with Petrocom and SOLA Communications to form
and the network was converted to GSM.
Telefónica Servicios Uno since 1971, Moviline since 1994)
was the analogue service provider for the Spanish operator. Moviline
has operated an E
TACS 900 (mHz) network in Spain. Since 31 December
2003, the system has been closed to new users, at that time, it
covered 100% of the Spanish population, but now some antennas have
been given to
GSM operators. The Moviline brand has been completely
replaced by Movistar, the digital brand of Telefónica, since 1992.
The network was completely converted to
GSM and its in all Spanish
Movistar have a 3G network with Universal Mobile
Telecommunications System(UMTS) technology, and offer services over
GSM in places without 3G coverage.
AT&T Mobility - In areas where AT&T Mobility previously had
D-AMPS operating on 1900
MHz frequencies, no analog AMPS network
existed, and the
D-AMPS network on the 1900
MHz frequency was
shut down in mid-2007. Service on the remaining 850
markets was discontinued along with 850
D-AMPS service on
February 18, 2008, except in areas where service was provided by
Dobson Communications. The Dobson AMPS and TDMA networks were shut
down on March 1, 2008.
Telecom New Zealand (now Spark New Zealand) - operated an AMPS/TDMA
network in New Zealand from 1987 until 2007 throughout the whole
country and the network was renowned for its superb coverage, In 2000
Telecom announced that they would discontinue the AMPS network within
5 years (2005) to give customers an opportunity to transition to the
CDMA2000 and later 1XRTT technologies that replaced it. They later
extended that deadline until 6PM 31 March 2007. At approximately 7:15
on March 31, 2007 the AMPS/TDMA network ceased to function.
Telstra (formerly Telecom Australia) - operated an AMPS network in
Australia from February 1987 until the end of 2000. As part of the
introduction of mobile phone competition in Australia, the Australian
GSM as the new standard for mobile networks, and
Telstra close the AMPS network by 2000. However, GSM
base stations could only serve a limited area. While this was OK for
Europe, it meant that
GSM could not cover large, sparsely populated
rural areas of
Australia cost effectively.
Telstra deployed a CDMA
network, which did not suffer this limitation, and while the AMPS
network was closed down at the end of 1999 in the major cities, the
closure deadline was extended until the end of 2000 in rural areas to
ease the transition to CDMA. The CDMA network has since been replaced
by an 850
UMTS network, Next G.
SaskTel - operated an AMPS network in Saskatchewan, Canada. It was the
third largest AMPS network, by subscribers, in the world at the time
of its turndown. It was officially shutdown site by site starting
at 00:00 on January 2, 2010 after twenty-one years of service. SaskTel
continues to run
Etisalat (previously known as Celltel / TIGO) - operated a Motorola
TAC network in Sri Lanka. It was the largest analog network in Sri
Lanka. The site was officially shutdown on October 31, 2006 after 17
years of service. Etisalat -
Sri Lanka continues to run
HSPA+(Evolved High-Speed Packet Access) networks.
Pelephone - began offering nationwide AMPS service in
Israel in 1986.
In the mid-1990s it converted to CDMA (
IS-95 and later EV-DO) and in
the mid-2000s converted to UMTS.
Singtel (previously known as Telecommunications Equipment) - operated
an AMPS network, marketed as a Cellular Mobile Radio System (CMRS), in
Singapore from 1988 until 1994. In 1989, Singapore's Mass Rapid
Transit (MRT) became the first rapid transit system in the world to
have full mobile phone coverage inside underground stations and
tunnels using AMPS technology.
Singtel decommissioned its AMPS
network in 1994 after
GSM was implemented.
Paktel was granted an AMPS licence in early 1990 to operate a cellular
telephone network throughout Pakistan. It was the first company
granted a free license to carry out cellular phone services in
Pakistan. It carried out AMPS services until 2004, after which it
switched to GSM.
History of mobile phones
Interview of Joel Engel
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Cellular network standards
List of mobile phone generations
0G (radio telephones)
MTA - MTB - MTC - MTD
AMPS (TIA/EIA/IS-3, ANSI/TIA/EIA-553)
IS-95 and ANSI-J-STD 008)
IS-54 and IS-136)
CDMA2000 1X (TIA/EIA/IS-2000)
CDMA2000 1X Advanced
UTRA-FDD / W-CDMA
UTRA-TDD LCR / TD-SCDMA
UTRA-TDD HCR / TD-CDMA
CDMA2000 1xEV-DO Release 0 (TIA/IS-856)
(3.5G, 3.75G, 3.9G)
CDMA2000 1xEV-DO Revision A (TIA/EIA/IS-856-A)
EV-DO Revision B (TIA/EIA/IS-856-B)
EV-DO Revision C
LTE Advanced (E-UTRA)
LTE Advanced Pro (4.5G Pro/pre-5G/4.9G)
WiMAX (IEEE 802.16m)
WiMax 2.1 (LTE-TDD)
List of standards
Comparison of standards
Channel access methods
Spectral efficiency comparison table
Cellular frequencies (Bands: