CDPD (cellular digital packet data)

An enhanced system overlay for transmitting and receiving data over cellular networks. Technology that allows data files to be broken into a number of "packets" and sent along open channels of existing cellular voice networks. (Cingular)

Cellular Digital Packet Data (CDPD) uses unused bandwidth normally used by AMPS mobile phones between 800 and 900 MHz to transfer data. Speeds up to 19.2 kbit/s are possible.

Developed in the early 1990's, CDPD was large on the horizon as a future technology. However, it had difficulty competing against existing slower but less expensive Mobitex and DataTac systems, and never quite gained widespread acceptance before newer, faster standards such as GPRS became dominant.

As of the year 2004, major carriers in the United States are threatening to shut down CDPD service. As of July 2005, the former AT&T Wireless CDPD network is no longer active, and Cingular Wireless CDPD customers have been informed that as of the end of the year, it will be down as well.

(Wikipedia)