1xRTT (Single-Carrier Radio Transmission Technology) is an operational mode for CDMA2000 wireless communications that specifies a single (1x) 1.25MHz channel for data transfer. 1xRTT was the first version of CDMA2000, which is the International Telecommunication Union's (ITU) CDMA (Code-Division Multiple Access ) implementation of the IMT-2000 standard. The theoretical network voice capacity of basic 1xRTT systems is approximately 144 kilobits per second ( kbps ) although in practice the highest attainable speed is more like 80 Kbps. Versions of CDMA2000 have been developed by Ericsson and Qualcomm.
See also: EV-DO , HSDPA