Today’s cellular technology offers several different methods for
data communications—an internal modem with built-in browser,
an internal modem with an external port for connection (typically
RS-232 or infrared (IR) to computer, or internal SMS
messaging.
Modems fall into two categories: CDPD or traffic channel.
CDPD offers true packet data communications at 19.2 Kbps
whereas modems using the traffic channels are limited to the
maximum rate for a traffic channel ( 14.4 Kbps, depending on
the standard). Future 2.5G and 3G networks will differ in two
distinct ways: Traffic channel rates will be higher, from 64
Kbps to 2.4 Mbps, and all data will be either packet-based or
high speed circuit-switched.