What's the difference between GSM and CDMA?
CDMA (Code Division Multiple Access) and GSM (Global System for Mobiles) are shorthand for the two major radio systems used in cell phones. The two cellular standards function in different regions and allow for global communication between individuals, and each converts incoming and outgoing data into radio waves differently. These two signals are by far the most dominant in the United States. As a result, jamming devices with both kinds of signals are mainstream in the United States
GSM stands for Global System for Mobile Communication, and unless you live in the United States or Russia, this is probably the technology your phone network uses, given it’s the standard system for most of the world. CDMA — or Code Division Multiple Access — is often found in the U.S and Russia.
Therefore, you must know the signal that needs to be interfered before you buy a cell phone jammer. Of course, the world's most popular mobile phone signal or 3G and 4G