#Pound key on cell phone trial
#Pound key on cell phone free

If all lines were in use, the switch would disconnect any non-priority calls, and then any Priority (D) calls.

#Pound key on cell phone free

For example, pressing C, Immediate, before dialing would make the switch first look for any free lines. Pressing one of these keys before you dialed your number gave your call priority over other conversations on the network. In this system the keys A through D were used to signal a call’s priority to the government’s PBX network: Flash Override (A), Flash (B), Immediate (C), and Priority (D), with Flash Override being the highest. The result was the Autovon phone system, used only by the Department of Defense and the White House. So when 8 is pressed, both frequencies are invoked, resulting in a dual-tone beep.Īs is often the cause with advances in technology, the government wanted to get involved and asked that the phone dial be adapted for special services. A four-by-four grid had to be used, as a three-by-three grid would have only allowed nine numbers, and you can’t let six good tones go to waste! Eight tones are used in the grid, as follows:įor example, the 8 key is located in the second column, which is assigned the 1336 Hz frequency, and the third row, which is assigned 852 Hz. The familiar dual-tone system in use today (called DTMF for “Dual Tone Multi Frequency”) came about when engineers realized that a four by four grid consisting of two simultaneously sounded tones of discrete non-harmonically related frequencies would be not only more reliable but more secure. The engineers who designed the Touch-Tone system envisioned it in the 1940s as a multi-tone system. “Octatherp” was proposed but wisely rejected in favor of “pound.” Calling the asterisk “star” was easy enough, but naming the other key was more of a challenge. The star and diamond were replaced with the asterisk and pound sign when one of the Bell System engineers decided the two extra keys on the dial should have characters drawn from the ASCII character set. (See “1963.”) The specs, however, called for a five pointed “star” key and a “diamond” key, along with four other keys labeled A though D. See a picture of this first push button phone here. The first phones only had 10 buttons, the numbers 1 through 0. The original Touch-Tone phones (not simply phones with buttons) were introduced to the American public in November 1963. Much research and testing remains to be done before the sets can be made in quantity and placed in service, but these may be the telephones of the future.” – Telephone Almanac for 1960, Southern Bell Telephone and Telegraph Company/Bell Telephone System.

#Pound key on cell phone trial

These new sets were placed on trial last summer, then taken out of service for study at the Laboratories. Instead of twirling a dial, users will press numbered buttons to make a call – a faster process than dialing. “A pushbutton telephone that may eventually replace the conventional telephone dial is under development by the Bell Telephone Laboratories. Dear Straight Dope: What is the history of the pound and star symbols on the phone keypad? I understand their use today for automated systems, but why were they originally added to the phone? Al