For operating in these microwave frequencies they all need some access methods. And these methods are:
1. Frequency division multiple access (FDMA)
2.Time division multiple access (TDMA)
3.Code division multiple access (CDMA)
GSM is nothing but a global standard for TDMA. GSM is a widely spread standard and CDMA is a patented technology. That is you must pay a royalty for using CDMA! Also GSM covers the entire Europe , Asia except Korea, Africa and Middle East. So being a GSM user you have virtually an international roaming. You can eazily use a GSM phone in any of these countries while roaming. GSM users are almost 8 times in number than CDMA users worldwide. By being a GSM user you will be part of the largest mibile community. And coming to voice quality GSM is far better than CDMA. CDMA base stations consumes less power than GSM and also covers a large distance. That is the cell size in CDMA is larger compared to GSM.
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