Wireless
Phones - Discount Wireless Phone and Accessories
Guide
In telecommunication,
a wireless phone, handy, cellular mobile or cell phone (in the United
States) is also called a mobile phone in other English speaking
countries
A Wireless
Phone is a mobile communications system that uses a
combination of radio wave transmission and conventional telephone
switching to permit telephone communication to and from mobile users
within a specified area.
The term does not comprise the so-called portable
phone or cordless phone, which is associated with a fixed telephone
landline and can only be operated close to (less than 100 metres
of) its base station, such as in and around the house (see telephone
for more). The term cell phone applies specifically to mobile phones
which use a cellular network; satellite phones are also mobile phones,
but not cellular (see the Iridium satellite system).
A cell phone is a portable telephone which receives
or sends messages through a Cell site, or transmitting tower. Radio
waves are used to transfer signals to and from the cell phone. Each
cell site has a range of 3-15 miles and overlaps other cell sites.
All of the cell sites are connected to one or more cellular switching
exchanges which can detect the strength of the signal received from
the telephone.
As the telephone user moves or from one cell
area to another, the exchange automatically commands the handset
and a cell site with a stronger signal (from the handset) to go
to new radio channels
When the handset responds through the new cell-site,
the exchange switches the connection to the new cell-site. With
CDMA technology, the process is slightly different. CDMA handsets
are not assigned a specific "channel"; they instead send
each bit using a pseudo-random code sequence specific to each phone.
As the user moves from one cell to another, the handset actually
connects to both sites simultaneously. This is known as a "soft
handoff" because, unlike with traditional cellular technology,
there is no one defined point where the phone switches to the new
cell.
Modern mobile phones use cells because radio
frequencies are a limited, shared resource. Cell-sites
and handsets change frequency under computer control and use low
power transmitters so that a limited number of radio frequencies
can be reused by many callers with less interference. CDMA handsets,
in particular, must have strict power controls to avoid interference
with each other. An incidental benefit is that the batteries in
the handsets need less power.
The term "cell phone"
is uncommon outside of the US. However, almost all mobile phones
use cellular technology, including GSM, CDMA and the old analog
mobile phone systems. Hence, many people use the term "cell
phone" to mean any mobile telephone system. The exception to
mobile phones using cellular technology are satellite phones.
The Iridium phone system is very like a cell phone
system except the cell sites are in orbit. The marine radio telephone
satellites administered by INMARSAT have a completely different
system (see below).
Old systems pre-dating the cellular principle may
still be in use in places. The most notable real hold-out is that
many amateur radio operators maintain phone patches in their clubs'
VHF repeaters.
Early mobiles were analog; newer ones are digital.
The first digital cellular phone call was made in the United States
in 1990.
There are a number of different digital cellular
technologies; these include: GSM, CDMA (Code Division Multiple Access),
DECT, IS-136, and iDEN
Mobile phone technology is often divided into generations:
1G, 2G, 2.5G, and 3G: Click for Wireless
Glossary
1G: NMT, AMPS, TACS 2G: IS-136 ("TDMA"), IS-95 ("CDMA"),
GSM, iDEN 2.5G: GPRS
3G: EDGE, UMTS, CDMA2000 PCS is often mistakenly referred to as a different
2G technology. It is not. PCS is an acronym for Personal Communications
Service, which merely represents the 1900 MHz spectrum set aside
by the FCC in America for additional wireless phone capacity. GSM-1900,
IS-95, IS-136, and CDMA2000 operate on the 1900 MHz PCS band today.
The other spectrum used in North America (850 MHz)
was the original spectrum licensed by the FCC in the 1980s, commonly
referred to as Cellular spectrum. Today, AMPS, IS-95, CDMA2000,
IS-136, and more recently GSM-850 all operate on the Cellular spectrum.
All of these technologies were based on cellular
technology. However, satellite based phones are called mobile phones
too.
Major mobile phone manufacturers include Nokia,
Sony Ericsson, LG, Motorola, and Samsung
Many mobile phones support 'auto-roaming', which
permits the same phone to be used in multiple countries. However,
both countries must use the same mobile system and the same frequencies
(this is an important issue for GSM users traveling between North
America and the rest of the world), and there must be an agreement
between the two countries' telephone operators. Click for GSM
Phone Roaming FAQs
In the UK, Australia and New Zealand, mobile phones
are often called simply mobiles. In Germany, they are called Handys,
in Switzerland Natel. In Sweden, they are sometimes called nalle,
or teddy bear, referring to the fact that many people always carry
them around and feel insecure if they misplace them.
Mobile phones must be distinguished from portable
phones (called cordless phones in the US); with a portable phone
the user purchases their own base station, which they connect to
a landline, the range of the phone is generally restricted to under
50 m, and the phones operate on a different frequency and protocol
(e.g. DCTS in North America; DECT in Europe).
Mobile phones do not only support voice calls; they
can also send and receive data and faxes (if a computer is attached),
sending short messages (or "text messages"; see Short
Message Service), access WAP services, and provide full Internet
access using technologies such as GPRS. Mobile phones often have
a clock and a calculator and often one can play some games on them.
Newer models also allow for sending pictures
and have a built-in digital camera - This gives rise to
some concern about privacy, in view of possible voyeurism, for example
in swimming pools. For this reason, Saudi Arabia has banned camera
phones entirely; South Korea has ordered manufacturers to ensure
that all new handsets emit a beep whenever a picture is taken. Many
swimming pools have banned camera mobile phones in their pools and
changing rooms. On the other hand, cameras can be used by crime
victims or witnesses to help identify the criminals.
GPS receivers
are starting to appear in cell phones, primarily to aid in dispatching
emergency responders.
Newer models have included many features aimed towards
personalization, such as user defined ring tones and operator logos,
and interchangeable covers, which have helped in the uptake by the
teenage market.
Usually one can choose between a ring
tone and a vibrating alert.
