Some cell phones can only work with the CDMA-based networks used by Verizon, Sprint and U.S. Cellular.   Other cell phones can only work with the GSM-based networks used by AT&T and T-Mobile.  A study report suggests that GSM cell phones have a much greater impact on the brain activity than CDMA cell phones.  As a growing body of evidence suggests that cell phone radiation can induce brain cancer, should the type of a cell phone be something a cell phone buyer need to consider when he purchases a cell phone?