Global System for Mobile Communications (GSM)

•Designed to be a digital (wide area) wireless network. • Driven by European telecom manufacturers, operators, and standardization committees • Very widely used around the world GSM Features 1.Service portability • Mobile can be used in any of the participating countries with international roaming and standardized numbering & dialing (but possibly at different rates!) • [...]

Cellular Digital Packet Data (CDPD)

In 1992, AT&T Wireless Services developed cellular digital packet data (CDPD) protocol, a data-only protocol that (re-)uses the AMPS or IS-136 network. Packets (typically some 1.5 kilobytes) use vacant cellular channels – either an assigned channel or between calls. CDPD does not communicate with the underlying network (but does utilize knowledge of this networks channel [...]