IS95

IS-95, also known as cdmaOne, is a second‑generation (2G) mobile telecommunications standard that uses direct-sequence spread-spectrum CDMA. Developed by Qualcomm, it was first released in 1995 and became the basis for a family of related standards (including IS-95A and IS-95B). The standard was formalized by the United States Telecommunications Industry Association (TIA) and was widely deployed in North America, parts of Asia, and elsewhere before being superseded by CDMA2000.

Technology: IS-95 employs direct-sequence spread spectrum to share a 1.25 MHz radio channel among many users. Each user is distinguished by a pair of codes: a common PN spreading sequence for all transmissions and an orthogonal Walsh code to separate logical channels. The system features forward and reverse links, support for downlink power control, and soft handoff between cells, which reduces dropped calls in areas of overlapping coverage.

Data and services: The original IS-95 offered voice alongside circuit-switched data at up to about 9.6 kbps per user. IS-95A refined interoperability and performance, while IS-95B later introduced higher peak data rates and improved efficiency. The standard primarily supported circuit-switched services, with data enhancements evolving through subsequent CDMA-based generations.

Deployment and legacy: IS-95 was widely deployed by operators in the United States, Korea, and other regions, forming the early CDMA mobile ecosystem. It provided the foundation for the CDMA2000 family (IS-2000), which extended data capabilities and moved 3G forward. Today, IS-95 networks have largely been supplanted by CDMA2000 and newer mobile technologies.

See also and variants: The name IS-95 refers to Interim Standard 95; related versions include IS-95A and IS-95B. In commercial use, the technology is commonly termed cdmaOne, distinguishing it from later CDMA2000 implementations.