Code Division Multiple Access cellular networks provide more bandwidth than Global System for Mobile Communications networks of the same generation and don't suffer from a distinctive buzzing common in GSM networks, resulting in higher overall call quality. CDMA phones are also locked to a specific network, a feature advantageous for service providers but inconvenient for customers.
The primary difference between CDMA and GSM technologies is that CDMA phones use a transmission protocol that encodes multiple calls into a single data burst and sends them all at once, while GSM networks send only one call at once and rapidly switch between calls to transmit multiple calls simultaneously. CDMA networks therefore allow for better data compression and higher-quality transmission than GSM networks.
However, GSM networks have undergone significantly more development than CDMA technologies, largely since GSM networks are used in most of the world while CDMA networks are mainly used by North American companies. All fourth-generation cellular networks are based on the GSM standard, while no 4G networks use CDMA technologies. Though the overall quality of CDMA calls is better than that of calls over a similar GSM network, the quality and bandwidth available over a GSM 4G network exceeds that of even advanced 3G CDMA networks.