Telephone Terminology: What Does It All Mean?

When Alexander Graham Bell invented the telephone, he did more than create an object of amusement. He created a tool that has become the primary means of alerting public safety. In addition to traditional telephony, telephone lines and technology have...


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When Alexander Graham Bell invented the telephone, he did more than create an object of amusement. He created a tool that has become the primary means of alerting public safety. In addition to traditional telephony, telephone lines and technology have played a supporting role in street boxes, automatic alarms, cellular service and, most recently, Voice over Internet Protocol (VoIP). Without the telephone, our society would certainly be different, and we might still be alerted to alarms by banging on a locomotive rim.

However, with the rise of the telephone has come the rise of myriad terms and acronyms designed to describe this ever-diversifying technology. The following is a brief description of the more important facets of telephony that we sometimes take for granted.

The heart and soul of telephony is the Public Switched Telephone Network (PSTN). This is the composite conglomerate of all the overhead and underground wires as well as the central offices and switches needed to provide dial tone and route calls. At one point, almost all of this network was owned and services were provided by AT&T and/or Bell Telephone, but on Jan. 1, 1984, a federally mandated divestiture reduced AT&T’s assets by over 75% and its employees by two-thirds.

The immediate impact was to open up long-distance competition, but over the years the effects have been more widespread. Where typically one telephone company provided service to an area, now there are many Local Exchange Carriers (LECs) that supply dial tone. Occasionally, reference will be made to the dominant LEC, as the one having the most market share, or to Alternate Local Exchange Carriers (ALECs) or Competitive Local Exchange Carriers (CLECs), but the distinction sometimes blurs. The bottom line: if you provide dial tone, you are a LEC.

Another development of divestiture was the opening of the Customer Premise Equipment market. The Regional Bell Operating Companies (RBOCs), or “Baby Bells,†now found themselves with two divisions – network and equipment – and it often took two calls to find the right person to fix the problem. For a residential customer, this eventually translated into the ability to buy telephone equipment at most any department or electronics store, rather than renting or purchasing it from the telephone company. For business and public safety, it has opened the gates to numerous third-party suppliers and competitive technology.

But 16 years earlier, another federal act also had tremendous impact upon public safety – the creation of 911. While not officially recognized as the national emergency number until the passage of Senate Bill 800, The Wireless Communications and Public Safety Act of 1999, the first 911 call was made in Haleyville, AL, in 1968. This came after a recommendation from President Johnson’s Commission on Law Enforcement and Administration of Justice the previous year that a nationwide number be established for law enforcement.

There are a variety of anecdotes as to how 911 was chosen, but it seems clear that the first official mention of those particular digits came from AT&T. The formal government proposals never identified a specific number. Some of the more likely explanations are that no such area code existed at the time, and dialing two ones was fast and simple on the rotary telephones then in vogue.

The first 911 systems provided Basic 911, meaning that emergency calls could be made for free, even from a pay telephone, and a simple-to-remember number could be used. Add-ons, such as line capture, allowed the seizure of a call to initiate a trace, automatic ring-back to recall a disconnected party and forced disconnect to terminate calls where required. Down the road, Enhanced 911 was implemented, and brought with it many important features. Automatic Number Identification (ANI) gave dispatchers immediate callback information. In our current age of caller ID this may sound trivial, but it was and still is a lifesaving feature. ANI associated with 911 calls comes from a different database than does caller ID, and unlike caller ID, it cannot be blocked.

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