Unlike GSM phones that work with a SIM card inside, the CDMA phones do not work based on a SIM.
Code Division Multiple Access ( CDMA)ĬDMA networks are the most common in North America and parts of Asia (CDMA networks examples: Verizon, Sprint, US Cellular, Straight Talk, Unefon). Indeed, there were set up some mergers between GSM and CDMA companies ( T-mobile and MetroPCS, Sprint and SoftBank ), but the most CDMA devices will not be compatible with GSM networks. This means you cannot use a Verizon phone with a GSM network inside the US, but you can use it with a GSM network in another country if you travel abroad. In some cases, CDMA phones might have a SIM slot, but they support only foreign GSM network. That means you can only switch CDMA phones with your carrier’s permission. GSM phones can be unlocked and switch carriers, whereas CDMA carriers use network-based white lists to verify their subscribers. Global System for Mobile Communication ( GSM)