In TDMA, the available spectrum is sliced into a number of frequency channels, each of which is shared by multiple users at one time. TDMA maintains separate frequency channels, subdivided in time. TDMA allows efficient utilization and permits digital islands to be installed where necessary to support the existing analog network. CDMA is a variation on spread spectrum developed for military communications. Each user is assigned a unique code to identify and separate calls sharing the same frequency at the same time.
Users share one wide frequency band, using unique codes to identify and separate calls.
GSM is the operating cellular system in many countries outside the United States where subscribers roam without borders. GSM offers the convenience of one phone number enabling users to be contacted wherever they may be traveling, providing GSM coverage is available. TDMA phones are idle between bursts, consuming less power than analog phones. Subscribers can talk nearly twice as long without a battery change. This method dramatically reduces the chances of call disruptions during handoff or of dropped calls due to a failed handoff.