CDPD is a system for packet data transmission that uses idle voice channels of the AMPS or IS-54 U.S. cellular phone system.
Applications of CDPD include
electronic mail
telemetry, for instance remote inventory reading of vending machines
Mobile end systems, the portable subscriber device
Mobile data base stations, located at cell sites that are also used for telephony.
Mobile data intermediate system, to perform routing to higher-layers or routers and gateways,
including routing over the backbone communication network.
