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Digital Cellular
A cost-cutting, long-distance walkie-talkie -- oh, and it's a cell phone, too

By Theo Gantos

Ever been shocked by the size of your cellular phone bill? Who hasn't? Well there's a new technology that is sweeping through the industry. Your present cellular provider may be reluctant to discuss digital cellular because their revenues are going to drop dramatically.

How does regular (analog) cellular service work? When you place a call you grab a frequency pair (one for transmit, one for receiving) from your local "cell" or transceiver which you tie up until you leave the service area for that cell and it hands you off to the next cell or you hang up. Your voice travels over the air much like on a CB radio. This is analog transmission. It's noisy, prone to disconnects, and ties up one frequency pair per call. To talk clearer you need more power, a better antenna, etc. Roaming is like making a long distance phone call, they turn your voice into digital data and send it along to the destination exchange, where it is turned back into audio and put over a wire or on the air. Since frequencies are limited and transceivers are expensive, you can see why your bill is so high.

Digital cellular throws the book away on old mobile phone technology. As you speak, your voice is "sampled" or turned into numbers representing sounds much like in a CD recording. Since these are numbers and not voices, ordinary scanners will hear nothing but pulsating noises. Next this data is squeezed or "compressed" using a mathematical formula to reduce the size of the packets. At the same time, many systems like Motorola's IDEN also scramble or "encrypt" the individual data "packets", making it very difficult to eavesdrop on conversations unless you have access to a supercomputer at the CIA or NSA.

Some systems can also add some additional data codes or "redundancy" allowing equipment at the receiving end to reconstruct information that may be lost or garbled in transmission.

Since your voice is now numbers, you send information only when you speak. A telephone conversation between two persons actually has a lot of silent pauses in it so nothing is sent during these pauses.

Since these transmitters can handle more information than one call requires, several calls can be handled on one frequency by intermingling the packets.

Using digital packets permits other services to be delivered at the same time. Alpha and numeric pager messages, email, even internet info! And you only pay for the time you actually use.

No more keeping track of bad reception redials to get credit from customer service. Digital cellular gets excellent reception.

Nextel (www.nextel.com) is the first company to offer digital cellular service in West Michigan. the Paper. spoke with James Cook, President of Preferred Telecommunications Corp., an authorized agent for Nextel Cellular in Michigan.

Cook said that "Motorola (www.mot.com) owns 25 percent of Nextel, a significant stake is also owned by billionaire Craig McCaw (who founded McCaw Cellular and then made a bundle when it sold to AT&T). And, he said, Nextel is the only company to offer the free "direct connect" feature."

Direct Connect works like a walkie-talkie with unlimited range. You select the person , who also must have a Nextel phone, and select direct connect. Then the other person receives an alert that they are being called by you. They can then call you by pressing a transmit button on the side of the phone.

Only one person can talk at a time, but there is no additional per minute charge to use this feature. The service is $55 a month with a rate of 19 cents per minute for regular cell phone calls, with NO roaming charges. Cook said that "you can get all this without any long-term activation contract, just month-to-month service."

I was quite impressed while trying this service, thinking of all the companies who can't afford two-way radios that are paying exorbitant monthly cell phone bills to use portable phones for communicating between their people internally. Nextel even has a group conference feature as part of the "direct connect" service which can broadcast your voice to several people at once. There are also enhanced features like call waiting, call forwarding, alpha paging, etc. available which are another by-product of it's digital heritage.

With this "new kid" on the block you can now see why many cellular providers have been offering fire-sale deals on phones and service as long as you sign your soul away for three years.

Theo Gantos is president of TEKA, a technology consulting firm. Contact him: