Wednesday, March 30, 2005

How Pagers Got Their Beep

The modern commercial paging service got its start with a family medical emergency in the early 1920s. Sherman Amsden couldn't reach his doctor who was out of the office and didn't have a secretary to answer the phone. Amsden decided the way to solve that problem was to have a central operator answer doctors' phones and take messages. The doctors could call in from wherever they happened to be and get their messages. He named his telephone answering company Telanserphone. The service was a commercial success, but doctors were still hard to get in touch with. That lead to the next advance, the radio pager.

Amsden teamed up with inventor Richard Florac to create with a two tube radio receiver in a plastic box that could be easily slipped into a coat pocket. Aircall was the first radio paging service, but it didn't get launched until 1950 and it didn't beep. Instead, subscribers would turn on the receiver from time to time and listen to a repeating series of numbers. If they heard their 3 digit code, they knew a message was waiting.

Another prolific inventor, Al Gross, also came up with a pocket pager in 1949, which was used by the Jewish Hospital in New York starting in 1950.

Basic "beepers" are not that far removed from that early technology. They still contain a radio receiver that operates in the VHF or UHF bands. They've shrunk to about half the size of Florac's ingenious receiver design. Solid state technology lets the pager take over the job of listening for the code numbers, now called capcodes, so you don't have to. The simplest pagers emit a beep when they hear their assigned code number. That's where they got the nickname "beepers." For silent operation, a motor with an off-center flywheel was added so that the entire pager would vibrate to indicate a message.

Motorola has been the big name in pagers ever since that term was first used to describe a Motorola system in the 1950s. The Motorola developed FLEX (FLEXible wide area synchronous protocol) signaling standard introduced in 1994 is the protocol of choice for one-way numeric and alphanumeric pagers. The complementary ReFLEX standard is used for two-way messaging. Both operate in the 900 MHz band on channels that are multiples of 25 KHz wide.

The traditional tone pager beeps or vibrates while the numeric pager also displays phone numbers and other numerical messages on a small liquid crystal display. The alphanumeric pager has an upgraded display that can show text messages. All of these are one-way pagers. They only have a radio receiver and decoder, so the paging service has no way of knowing if you actually received your message. They typically have better signal penetration into buildings than cell phones, but that doesn't mean they're sure to work down in the sub-basement. If you absolutely want to make sure you get your messages, you need a two-way pager.

The difference between one-way and two-way paging is the addition of a transmitter within the two-way pagers. This adds a couple of important new capabilities. First, you can send messages as well as receive them. Two-way pagers have little keyboards as well as multi-line displays. Second, a two-way pager can respond to the paging service to acknowledge receipt of a message. If you happen to be flying coast to coast when somebody sends you a text message or page, the system will keep trying to reach you until you have landed and are in range of a paging tower. The deluxe setup is a two-way pager with nationwide paging service.

More than 50 years after its introduction, radio paging has grown to millions of users all over the world. Pagers are a simpler and less expensive technology than cellular phones. You may prefer to get non-intrusive alerts and messages via pager rather than always engage in a voice conversation. The deaf and hard of hearing find two-way pagers to be an enabling technology.

Update: As of 2010, the functions of pagers have been largely replaced by cell phones and smart phones. Use the Cell Phone Plan Finder to check out the top phones and associated wireless service plans.

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