Web-ready phones make lots of noise with their own vocabulary

Web-ready phones make lots of noise with their own vocabulary

When comparing the offerings of different wireless service providers and phone sets, keep in mind the following terminology:

Analog cellular. The first cellular phone system, called the Advanced Mobile Phone Service, was analog and was initiated commercially in the United States in 1983. AMPS networks use FM radio signals at 800 MHz.

An AMPS cellular network comprises individual coverage areas, each with its own tower. Calls can be handed off from cell site to cell site for wider coverage, and a mobile telephone switching office converts the radio signals to transfer them to landline networks.

AMPS networks offer roaming'calls beyond the subscriber's coverage area'and a few basic features, but generally provide few advanced features such as call waiting and voice mail. AMPS calls can quite easily be intercepted or pirated, and dropped connections are commonplace as calls are passed from cell to cell.

CDMA. Code Division Multiple Access technology was made popular by Qualcomm Inc. of San Diego and operates in the 800-MHz and 1,900-MHz frequency bands. It is a digital technology that employs a shared portion of the spectrum band to transmit multiple signals simultaneously by assigning a code to each conversation.

CDMA provides more than 10 times the calling capacity of AMPS technology and from three to five times the capacity of GSM and TDMA. It provides security from signal pirating, and CDMA phones offer many calling features, excellent call quality and long battery life. CDMA2000 represents third-generation CDMA that will offer a minimum of 144-Kbps throughput and will be followed by 1.5-Mbps throughput.

CDPD. Cellular Digital Packet Data is a wireless transmission technology that provides a digital packet overlay on existing AMPS cellular networks. It offers data transmission speeds of 19.2-Kbps and is still popular for law enforcement and public safety applications and for point-of-sale terminals.

Dual-band, tri-band, quad-band. These are types of wireless Web phone handsets that can operate over more than one technology and radio band, such as 800-MHz or 1,900-MHz CDMA or 800-MHz AMDS.

GSM. The Global Standard for Mobile communications has been widely adopted in Europe, Japan, Australia and the Middle East, though it has never really caught on in the United States. It generally operates on the 900-MHz and 1,800-MHz frequencies. GSM subscriber data is carried on a subscriber identity module, a smart card that is inserted in a GSM phone.

IDEN. The Integrated Dispatch Enhanced Network is a wireless digital technology developed by Motorola that operates in the 800-MHz, 900-MHz and 1,500-MHz radio bands. It supports a wide number of services, including voice, radio, numeric paging and short-messaging service for text, data and fax transmissions.

PCS. Personal Communications System is a wireless digital transmission technology that operates on the 1,900-MHz radio band and offers excellent security and long battery life on exceptionally small handsets. It is available on TDMA, GSM and CDMA systems, though Sprint PCS' CDMA-based network is the most popular in the United States.

TDMA. Time Division Multiple Access separates multiple simultaneous conversations over a single frequency by assigning them different time slots. It operates in the 800-MHz and 1,900-MHz frequency bands and like CDMA is an efficient technology that offers many calling features and excellent sound quality.

WAP. The Wireless Application Protocol is a set of standards for providing Internet information and services to mobile phones, smart phones, pagers, personal digital assistants and other wireless devices. Phone.com Inc. of Redwood City, Calif., makes the most popular WAP browser, server and developer software applications. Any handset manufacturer or service provider can customize them for use with their systems.

3G. Third-generation wireless technology will transform today's mobile communications handsets into multimode, multi-band devices capable of providing seamless connections across regional and national boundaries at low cost to users.

'J.B. Miles

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