This protocol is also known as IS-95. CDMA differs from GSM and TDMA by its use of spread spectrum techniques for transmitting voice or data over the air. Rather than dividing the radio frequency spectrum into separate user channels by frequency slices or time slots, spread spectrum technology separates users by assigning them digital codes within the same broad spectrum. Advantages of CDMA include higher user capacity and immunity from interference by other signals. Available in either 800 or 1900 MHz frequencies.