CDPD - Cellular Digital Packet Data
Cellular Digital Packet Data (CDPD) is an add-on technology that enables U.S. first generation (1G) and second generation (2G) mobile communication systems to provide packet data.
CDPD uses the full 30 kHz AMPS channels in the 800 MHz band. CDPD occupies voice channels on a purely secondary, non interfering, basis. Packet channels are dynamically assigned to voice channels as they become vacant. So, the CDPD radio channels vary with time.
The CDPD network is an overlay on the existing network. It uses the existing base stations making it simple and inexpensive to install. CDPD is an IP network that runs at 19.2 kbps, with a typical throughput of around 10kbps.
CDPD was phased out with the rise of 2.5G and 3G systems.