. . . and knowing the technology

To make sense of wireless service plans, it helps to have a basic understanding of the underlying technology.

Wireless telephone service breaks down into two different technologies (digital and analog); two radio frequencies (800 MHz for cellular, digital and analog; and 1900 MHz for PCS, which is digital); and four different standards for transmission, none of which are compatible with the others. You can choose among:

Analog (AMPS) -The original cellular service, analog dates back to 1982 and today covers most of the country. CellularOne and most Baby Bells offer analog plans.

CDMA (Code division multiple access) - Gives the clearest digital signal, experts say. The biggest nationwide carrier is Sprint, but coverage is limited.

TDMA (Time division multiple access) -The most popular digital standard is used by many carriers, including AT&T, CellularOne, and Nextel.

GSM (global system for mobile) -The digital standard in Europe, it also offers good coverage in many US metro markets. AirTouch, Omnipoint, and PacBell are the biggest providers. It encrypts calls and lets you use the same number and account in Europe.

Before choosing a phone or service plan, make sure you know what your phone is capable of doing while traveling.

(c) Copyright 1999. The Christian Science Publishing Society