Cell Phone Network Technologies:

There are three common technologies used by 2G cell-phone networks for transmitting information (we'll discuss 3G technologies in the 3G section):
Frequency division multiple access (FDMA)
Time division multiple access (TDMA)
Code division multiple access (CDMA)

Although these technologies sound very intimidating, you can get a good sense of how they work just by breaking down the title of each one.
The first word tells you what the access method is. The second word, division, lets you know that it splits calls based on that access method.
FDMA puts each call on a separate frequency.

TDMA assigns each call a certain portion of time on a designated frequency.

CDMA gives a unique code to each call and spreads it over the available frequencies. The last part of each name is multiple access. This simply means that more than one user can utilize each cell.
FDMA separates the spectrum into distinct voice channels by splitting it into uniform chunks of bandwidth. To better understand FDMA, think of radio stations: Each station sends its signal at a different frequency within the available band. FDMA is used mainly for analog transmission. While it is certainly capable of carrying digital information, FDMA is not considered to be an efficient method for

In FDMA, each phone uses a different frequency.