A method for data transmission over analog Advanced Mobile Phone System (AMPS) cellular radio networks. CDPD takes advantage of the natural idleness between disconnections and connections during the break and make process to transmit packetized data at rates up to 19.2 kbps, using either the Internet Protocol (IP) or the ISO Connectionless Network Protocol (CLNP). The frequency-agile CDPD modems search for available channels over which to send encrypted packets during the periods of channel idleness. Ultimately, CDPD proved too complex, too bandwidth-limited, and too expensive, especially as data-ready 2.5G and 3G networks made their appearances and analog cellular networks were phased out.The last of the CDPD networks were decommissioned around the end of 2005. See also AMPS, analog, break and make, cellular radio, CLNP, encryption, IP, ISO, and modem.
(Cellular Digital Packet Data) An earlier low-speed wireless data network used from the early 1990s to the mid-2000s. Based on IBM's CelluPlan II, CDPD transmitted IP packets in the unused voice channels of analog cellular networks at 19.2 Kbps. If all channels were busy, the data were stored and forwarded when a channel became available. Used for police data networks, public safety terminals and telemetry, CDPD modems were available for laptops via PC Cards and for Apple's Newton and Palm PDAs. See DataTAC, Velocita Wireless and Ricochet.