TDMA is used in second-generation (2G) cell phone systems such as GSM. Most major third-generation (3G) cell phone systems are primarily based upon GSM rival CDMA. 3G allows for faster data speeds over 2G.
While TDMA and CDMA both achieve the same goal, they do so using different methods. TDMA technology works by dividing each digital cellular channel into three time slots for the purpose of increasing the amount of data carried.
Multiple users, therefore, can share the same frequency channel without causing interference because the signal is divided into multiple time slots.
While each conversation is transmitted alternately over short lengths of time with TDMA technology, CDMA separates communications by code so multiple calls can also be routed into the same channel.
The major cell phone carriers in the U.S. no longer use TDMA. Sprint, Virgin Mobile and Verizon Wireless use CDMA while T-Mobile and AT&T use GSM.