1xRTT
1x (single-carrier) Radio Transmission Technology
The first in a family of cdma2000 1x digital wireless standards designed to extend and replace the original IS-95 CDMA 2G standard. 1xRTT is sometimes referred to as a "2.5G" standard.
1xRTT was replaced by 3G technologies such as 1xEV-DO, and 4G technologies such as LTE.
Compared to the IS-95 CDMA technology it replaced, 1xRTT offered increased network voice capacity. This benefit required support on both the base station (tower) and handset (phone). If everyone using a given tower has a 1xRTT phone, twice as many people can use that tower at the same time, compared to the old IS-95 standard.
1xRTT also offers much faster data speeds compared to IS-95. The initial release - release 0 (zero) - supported data speeds peaking at 144 kbps. Typical real-world speeds were closer to 60-80 kbps.
A second release of 1xRTT was planned - release A - which doubled data rates at 288 kbps peak. Many carriers chose to skip 1xRTT release A, however, and move directly to the much faster 1xEV-DO, a 3G technology.
See: 1xEV-DO
See: CDMA
Last updated Jul 6, 2017 by Rich Brome
Editor in Chief Rich became fascinated with cell phones in 1999, creating mobile web sites for phones with tiny black-and-white displays and obsessing over new phone models. Realizing a need for better info about phones, he started Phone Scoop in 2001, and has been helming the site ever since. Rich has spent two decades researching and covering every detail of the phone industry, traveling the world to tour factories, interview CEOs, and get every last spec and photo Phone Scoop readers have come to expect. As an industry veteran, Rich is a respected voice on phone technology of the past, present, and future.
