1x is third generation (3G) protocol, although some may consider it as 2.5 or 2.75G technology, meaning it provides some but not all of the benefits of 3G. In its full designation, CDMA2000 1xRTT, "CDMA" stands for "code division multiple access", while "1xRTT" stands for "1 times Radio Transmission Technology.

This technology was pioneered by a wireless telecommunications research and development company known as Qualcomm.

Of the four types of CDMA2000, 1x is the simplest and most basic type. It was introduced commercially in 1995, and had since become one of the fastest-growing wireless technologies in the world. 1x was a key stepping stone in wireless networking because it served as the basis for 3G wireless systems.

In CDMA, frequency channels are defined with pseudorandom number sequences, and multiple transmitters are permitted on the same channel simultaneously. This makes CDMA more favorable economically in contrast with frequency division multiple access (FDMA) and time division multiple access (TDMA), since CDMA can serve more phones on fewer sites while avoiding electromagnetic interference, static and cross-talk. 1x handsets also tend to have longer battery life since they transmit at the lowest possible power levels.

Wireless data transmission occurs in 1x by converting speech into digital information. This information is then transmitted as a radio signal over a wireless network.

1x uses a duplex pair of 1.25 MHz radio channels, giving it the same radio frequency bandwidth as IS-95. However, 1x has double the capacity of IS-95 since it has 64 more traffic channels in its forward link, as compared to IS-95’s original set of 64 traffic channels.

The additional 64 channels are positioned perpendicular to the original set of 64. Data is transmitted at speeds of up to 144 kbps. The data link layer of 1x provided greater use of data services, such as medium and link access control protocols and Quality of Service. The data link layer of IS-95, on the other hand, only provided "best effort delivery" for voice and data.