Analog cellular phones work off of the Advanced Mobile Phone Service, otherwise known as AMPS, system. This technology is the oldest, and therefore the most established, wireless system in the United States, covering about 95 percent of the country. It works by transmitting sound waves over radio waves, just like an FM radio dial.
Digital cellular phones offer more enhanced features than their analog predecessors. Digital technology converts speech into a sequence of ones and zeros over a narrow band of frequencies, and allows signals to travel up to three times faster than conventional analog. It also reduces background noise, the amount of dropped calls, and increases security.
Mobile or car phones can be used either as hand-held phones or as hands-free phones. Although many people are used to using a hand-held phone, this is not advisable when you're driving. In some states it's even illegal to use a hand-held mobile phone while driving.
Two basic categories of hands-free options for your wireless phone are car kits and portable accessories. Hands-free car kits enable you to talk without actually holding the phone, allowing you to focus on driving with both hands. A portable car kit plugs into your cigarette lighter adapter and has an external speaker and microphone.
Mobile phones or car phones take their power directly from the car battery. They're wired to the vehicle's ignition and shut off when the car is turned off, unless you have a feature called call-in-progress protection that lets you continue your call. The biggest advantage of a mobile phone is that it can transmit at a higher power level than a portable phone.
Personal Communications Service, or PCS, wireless phones are virtually identical to digital cellular phones. The only real difference is the name and the frequency on which they operate. PCS phones are usually referred to as 'wireless,' instead of 'cellular,' and operate on a 1900 MHz frequency range.
Portable or hand-held phones are the most popular wireless phone option, probably because they're the most versatile. All of a portable's components, including the antenna and radio transceiver, are built into the handset. You can carry one in your pocket or purse, and get a car-mounting kit and power booster to use when you're in your car.
A 'smart phone' is a common term used for digital wireless phones that are capable of sending and receiving data messages in addition to voice messages. Nearly all PCS wireless phones are smart phones, as are a few digital cellular phones. They offer such features as micro-web browsers, voice and e-mail, and the ability to receive faxes.