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type of multiplexing used. The main 2G standards are:

inhabited continents (Time Division Multiple Access). Today accounts for over 80% of
the 450 MHZ frequency band (CDMA450).[1]
Mexico, India, Australia and South Korea.
• PDC (TDMA-based), used exclusively in Japan
Mobility in Canada


2.5G services enable high-speed data transfer over upgraded existing 2G networks. Beyond 2G,
there's 3G, with higher data speeds, and even evolutions beyond 3G, such as 4G.

[edit] Capacities, advantages, and disadvantages

[edit] Capacity


voice encodings through the use of various codecs, allowing more calls to be packed into
the same amount of radio bandwidth.
that cells could be smaller, so more cells could be placed in the same amount of space.
This was also made possible by cell towers and related equipment getting less expensive.

[edit] Advantages

Digital systems were embraced by consumers for several reasons.

• The lower powered radio signals require less battery power, so phones last much longer
between charges, and batteries can be smaller.
• The digital voice encoding allowed digital error checking which could increase sound
quality by increasing dynamic range and lowering the noise floor.
• The lower power emissions helped address health concerns.
• Greatly reduced fraud. With analog systems it was possible to have two or more "cloned"
handsets that had the same phone number.
• Enhanced privacy. A key digital advantage not often mentioned is that digital cellular
calls are much harder to eavesdrop on by use of radio scanners. While the security
algorithms used have proved not to be as secure as initially advertised, 2G phones are
immensely more private than 1G phones, which have no protection against

[edit] Disadvantages

The downsides of 2G systems, not often well publicized, are:

• In less populous areas, the weaker digital signal may not be sufficient to reach a cell
National regulations differ greatly among countries which dictate where 2G can be
• Analog has a smooth decay curve, digital a jagged steppy one. This can be both an
longer and allowing at least a few words to get through.
used by the codecs takes a toll; the range of sound that they convey is reduced. You'll
hear less of the tonality of someone's voice talking on a digital cellphone, but you will
hear it more clearly.