What are the differences between GSM&CDMA networking? please exclaim me in details.?

GSM allows you to surf the web and talk at the same time. (such as AT&T - T-Mobile.). Verizon uses a technology that is CDMA, which will not allow you to multitask.. Just talk or surf..one or the other. CDMA does not use 'SIM' cards......GSM uses 'SIM' cards.. GSM means Global System for Mobile. CDMA is Code Division Multiple Access ..GSM being a relatively simpler technology, uses a lot less battery power than CDMA. GSM is an International standard, whereas CDMA is prominent in North America. You can buy a new GSM phone, using the same SIM card. A new CDMA phone requires all new programming, and most likely loss of all your info and contacts...Both are fighting for new technologies, but I feel GSM has the edge, hands down..!! AT&T and T-Mobile are upgrading to HSPA+ and 4G LTE in late 2011.. This will also make the 3G network of those carriers in much better shape when it rolls out next-gen. LTE Network.!!