Analog Service- A method of modulating radio signals so that they can carry information such as voice or data. Analog cellular phones work like a FM radio. The receiver and transmitter are tuned to the same frequency, and the voice transmitted is varied within a small band to create a pattern that the receiver reconstructs, amplifies and sends to a speaker. The drawback of analog is the limitation on the number of channels that can be used.
Digital Service- A method of encoding information using a binary code of 0s and 1s. Most newer wireless phones and networks use digital technology. In digital, the analog voice signal is converted into binary code and transmitted as a series of on and off transmissions. One of digital's drawbacks, is that there are three digital wireless technologies, CDMA, TDMA and GSM. Phones that work with one technology may not work on another.
TDMA- Released in 1994, TDMA IS-136 uses the frequency bands available to the wireless network and divides them into time slots with each phone user having access to one time slot at regular intervals. TDMA IS-136 exists in North America at both the 800 MHz and 1900 MHz bands.
GSM - 1987, the GSM standard was created based on a hybrid of FDMA (analog) and TDMA (digital) technologies. GSM engineers decided to use wider 200 kHz channels instead of the 30 khz channels that TDMA used, and instead of having only 3 slots like TDMA, GSM channels had 8 slots. This allowed for fast bit rates and more natural-sounding voice-compression algorithms. Sprint currently has the largest GSM network in the World.
IDEN - "Integrated Digital Enhanced Network" :
iDEN uses TDMA technology to split a 25 KHz frequency into six separate time slots. Using a combination of half-duplex and full-duplex signals, iDEN is able to provide:
