Cellular Digital Packet Data (CDPD)

Cellular digital packet data (CDPD) was a wireless data service used to access the Internet and other packet-switched systems over a cellular network. CDPD was normally used by analog advanced mobile phone system (AMPS) standards and was one of the first generation cellular frequencies.

From 1995 to 1996 the CDPD protocol was standardized to answer wireless Web service demands. The technology utilized idle or unused channels operating at 800-900 MHz carriers serving speeds of up to 19.2 kbps. The CDPD protocol was replaced by short message service (SMS), general packet radio services (GPRS) and 3-G technologies.

CDPD technology incorporates the following systems:

• Mobile End System (M-ES) - a mobile computing device with a built-in or attached CDPD modem.
• Mobile Data Base Station (MDBS) - a manager of radio frequency.
• Mobile Data Intermediate System (MDIS) - properly routes data packets between the CDPD network and M-ES.
• Intermediate System (IS) - the standard Internet Protocol (IP) router, which relays data packets.
• Fixed-End System (FES) - the final/end destination, which is a common host/server for receiving and processing data.

During the 1990s CDPD was collaboratively developed by several leading mobile carriers as a networking protocol. Their developers no longer exist, due to mergers, buyouts and industry consolidation.

Today CDPD is a part of mobile history because AMPS’ mobile telephony standard is obsolete. However, CDPD technology remains responsible for the unfolding of contemporary technologies utilizing data packet technology to transfer information through mobile networks.