Uhhh

Bunch of wrong info here i think

CDMA is a network access technology, a signal modulation technique used to enable resource sharing. As far as I know variants of CDMA have been used in 3G, 4G, 5G and this will continue in 6G. 2G constitutes GPRS and EDGE as data standards created by the GSM group, a standardising Committee of old. Now we have xGPP committees doing the same. GSM usually refers (in popular usage of the term) to a voice network. All use licensed bands. FDD and TDD (FDMA and TDMA) can be used orthogonal to CDMA and are also used to separate TX and RX from one radio to avoid self interference.

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Also SIM cards are just a network identifier code that you carry on the device. I think its codes are transmitted to the towers for all these standards, and most commonly operators require you to use one to allow handover between commercial networks and countries. It has nothing much to do with protocol level requirements or modulation standards like CDMA.