GSM dates to the 1980s, when analog cellular systems in Nordic countries experienced rapid growth that resulted in the development of a new digital cellular standard. After five years of effort, 13 network operators and administrators signed a charter for the standardization of GSM. At that time, GSM was referred to by its French name, Group Special Mobile, but it is now known on a worldwide basis as Global System for Mobile Communications.
The European version of GSM operates in the 900MHz band, which was avilable in countries that are members of the European commission. Unfortunately, the 900MHz band in the United States was not available, so the 1900MHz band is used by GSM personal communications system in the United States.
GSM represents a TDMA version of PCS. As a digital technology, voice is first compressed using a hybrid coder at approximately 13kps before the data is modulated. With this digital technolgy, you can connect a data source directly to a GSM cell phone without the use of a modem. However, the highest data rate that you can expect to obtain will be approximately 14.4kbps.
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