CDPD

Cellular digital packet data CDPD) was a connectionless cellular packet communication protocol designed to overlay the existing D-AMPS, IS-54 and IS-136 TDMA infrastructure. At 19.2 Kbps, CDPD was twice the speed of IS-130/135 and made possible simultaneous voice and data communications.

Ericsson R280 IS-136 TDMA phone with CDPD data and micro-browser.

Where IS-130/IS-135 was a circuit switched technology best suited for file transfers, CDPD was better suited for bursty use such as browsing the internet via micro-browsers built into phones.

Like IS-130/IS-135 data/fax, CDPD suffered similar problems of pricing, reliability and spotty coverage. These problems caused it to never catch on as a cellular data communications scheme although it did achieve modest success in machine-to-machine applications.

CDPD proved to be another interim second generation technology. By 2000, work was underway on third generation technologies and CDPD languished until it was finally phased out in 2005.