Published DateNot all that long ago, when you made a direct dialed long distance call, as you dialed the digits of the distant telephone, the switching equipment and the long distance facilities (the physical lines) were being established as you dialed. As you dialed the digit "1", the system knew it was long distance and it routed you to the nearest long distance switching center. As you dialed the subsequent numbers, "212" for example, that meant you were dialing into New York City, and the system established the physical linkage to get you to New York. The next digits you dialed, "393" for example, routed you to that particular central office. The last four digits you dialed specified the person or place you were calling. That completed the connection and established all the links in sequence. If the telephone line you were calling was busy, you would hear the busy tone, and the connections from your telephone to the one in New York City would be disconnected. If the phone line was not busy, the telephone would would ring. (Incidentally, the "ringing" that the caller hears, is not the same ring that is being generated at the called party's phone. The ringing sounds are generated independently at each end.)
The average elapsed time for dialing and ringing was about 23 seconds. That is called the "operating time". That doesn't sound like much but, if you consider literally hundreds of thousands of calls being generated each day, multiplied by that 23 seconds, it equates to a substantial number of facilities that are required just to accommodate the operating time. One other important point is that in an "analog" world, each time you dialed a long distance number, that fully occupied a telephone line.
But technology changes and in the early 1960s, a gentleman named Paul Baran invented the "packet". The first thing to know is that the packet is transmitted as a digital signal, not an analog one. Next, the packet can travel on any route, it doesn't have to be the most direct or in a particular sequence of facilities. In its early configuration, the packet size was 1024 bits in length and included the "address" to which the message was going, the "address" from which the message was sent, the sequence number of the packet itself, and the remaining bits in each packet carried the "information". The changes this discovery made possible are mind boggling.
First, in the telephone network, when the caller was dialing the digits, it was no longer necessary to follow the analog path and to physically establish all the links necessary to complete the call only to find out the line was busy, essentially wasting the 23 seconds of operating time and tying up a telephone line. A single packet contained all of the information necessary to travel (at the speed of light) to the distant central office and determine if the called telephone was busy or available. If that telephone was not busy, the packet essentially informed the system to establish the connection. All this happened in about one second. It is important to note that the digital line carrying the packet of information can also carry untold numbers of packets from other callers. The line can be "bit stuffed" with unrelated packets whereas the analog system permitted only one number sequence in each line. While this was a boon to the telephone companies, it was even more of a benefit to what was a fledgling Internet system.
The "packet" became the norm for internet transmissions. Each time we hit the "send" key on our computer, our outgoing message is sent in a series of packets, each with its to and from address and packet sequence numbers. As the message is sent, it is mingled with other messages bound to other end users, that have been bit stuffed into a digital line. The "routers", or switches, at the distant end, put the packets in proper order sequence as they are transmitted to the end users. Remember, all this is taking place at the speed of light.
The benefits of the "packet" are so great that it has allowed most of the long distance calls to be converted to digital packets, multiple calls/packets to be bit stuffed onto single lines, thereby increasing call quality and significantly diminishing the demand for addition facilities. It's called VOIP, voice over Internet protocol.
Faster. Better. Cheaper.
(Bob Meade is a Laconia resident.)