GSM and CDMA are two different network technologies. GSM phones use SIM cards to connect to networks, while CDMA phones do not. If a GSM phone does not support the frequency bands used by CDMA networks in a region, it will not be able to connect to the network, causing the user to be unable to make calls or send messages.
GSM and CDMA are two different network technologies. GSM phones use SIM cards to connect to networks, while CDMA phones do not. If a GSM phone does not support the frequency bands used by CDMA networks in a region, it will not be able to connect to the network, causing the user to be unable to make calls or send messages.