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Hub AI
DTMF signaling AI simulator
(@DTMF signaling_simulator)
Hub AI
DTMF signaling AI simulator
(@DTMF signaling_simulator)
DTMF signaling
Dual-tone multi-frequency (DTMF) signaling is a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. DTMF was first developed in the Bell System in the United States, and became known under the trademark Touch-Tone for use in push-button telephones, starting in 1963. The DTMF frequencies are standardized in ITU-T Recommendation Q.23. The signaling system is also known as MF4 in the United Kingdom, as MFV in Germany, and Digitone in Canada.
Touch-tone dialing with a telephone keypad gradually replaced the use of rotary dials and has become the industry standard in telephony to control equipment and signal user intent. The signaling on trunks in the telephone network uses a different type of multi-frequency signaling.
Before the development of DTMF, telephone numbers were dialed with rotary dials for loop-disconnect (LD) signaling, also known as pulse dialing. It functions by interrupting the current in the local loop between the telephone exchange and the calling party's telephone at a precise rate with a switch in the telephone that operates the dial spins back to its rest position after having been rotated to each desired digit. The exchange equipment responds to the dial pulses either directly by operating relays or by storing the digits in a register that records the dialed telephone number. Pulse dialing was possible only on direct metallic lines and was limited in physical distance by the amount of electrical distortions present. For signaling over trunks between switching systems, operators used a different type of multi-frequency signaling.
Multi-frequency signaling (MF) is a group of signaling methods that use a mixture of two pure tone (pure sine wave) sounds. Various MF signaling protocols were devised by the Bell System and CCITT. The earliest of these were for in-band signaling between switching centers, where long-distance telephone operators used a 16-digit keypad to input the next portion of the destination telephone number in order to contact the next downstream long-distance telephone operator. This semi-automated signaling and switching proved successful in both speed and cost effectiveness. Based on this prior success with using MF by specialists to establish long-distance telephone calls, dual-tone multi-frequency signaling was developed for end-user signaling without the assistance of operators.
The DTMF system uses two sets of four frequencies in the voice frequency range transmitted in pairs to represent sixteen signals, representing the ten digits and six additional signals identified as the letters A to D, and the symbols # and *. As the signals are audible tones, they can be transmitted through line repeaters and amplifiers, and over radio and microwave links.
AT&T described the product as "a method for pushbutton signaling from customer stations using the voice transmission path". To prevent consumer telephones from interfering with the MF-based routing and switching between telephone switching centers, DTMF frequencies differ from all of the pre-existing MF signaling protocols between switching centers: MF/R1, R2, CCS4, CCS5, and others that were later replaced by SS7 digital signaling. DTMF was known throughout the Bell System by the trademark Touch-Tone. The term was first used by AT&T in commerce on July 5, 1960, and was introduced to the public on November 18, 1963, when the first push-button telephone was made available to the public. As the parent company of Bell Systems, AT&T held the trademark from September 4, 1962, to March 13, 1984. It is standardized by ITU-T Recommendation Q.23.
Other vendors of compatible telephone equipment called the Touch-Tone feature tone dialing or DTMF. Automatic Electric (GTE) referred to it as "Touch-calling" in their marketing. Other trade names such as Digitone were used by the Northern Electric Company in Canada.
As a method of in-band signaling, DTMF signals were also used by cable television broadcasters as cue tones to indicate the start and stop times of local commercial insertion points during station breaks for the benefit of cable companies. Until out-of-band signaling equipment was developed in the 1990s, fast, unacknowledged DTMF tone sequences could be heard during the commercial breaks of cable channels in the United States and elsewhere.[citation needed] Previously, terrestrial television stations used DTMF tones to control remote transmitters. In IP telephony, DTMF signals can also be delivered as either in-band or out-of-band tones, or even as a part of signaling protocols, as long as both endpoints agree on a common approach to adopt.
DTMF signaling
Dual-tone multi-frequency (DTMF) signaling is a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. DTMF was first developed in the Bell System in the United States, and became known under the trademark Touch-Tone for use in push-button telephones, starting in 1963. The DTMF frequencies are standardized in ITU-T Recommendation Q.23. The signaling system is also known as MF4 in the United Kingdom, as MFV in Germany, and Digitone in Canada.
Touch-tone dialing with a telephone keypad gradually replaced the use of rotary dials and has become the industry standard in telephony to control equipment and signal user intent. The signaling on trunks in the telephone network uses a different type of multi-frequency signaling.
Before the development of DTMF, telephone numbers were dialed with rotary dials for loop-disconnect (LD) signaling, also known as pulse dialing. It functions by interrupting the current in the local loop between the telephone exchange and the calling party's telephone at a precise rate with a switch in the telephone that operates the dial spins back to its rest position after having been rotated to each desired digit. The exchange equipment responds to the dial pulses either directly by operating relays or by storing the digits in a register that records the dialed telephone number. Pulse dialing was possible only on direct metallic lines and was limited in physical distance by the amount of electrical distortions present. For signaling over trunks between switching systems, operators used a different type of multi-frequency signaling.
Multi-frequency signaling (MF) is a group of signaling methods that use a mixture of two pure tone (pure sine wave) sounds. Various MF signaling protocols were devised by the Bell System and CCITT. The earliest of these were for in-band signaling between switching centers, where long-distance telephone operators used a 16-digit keypad to input the next portion of the destination telephone number in order to contact the next downstream long-distance telephone operator. This semi-automated signaling and switching proved successful in both speed and cost effectiveness. Based on this prior success with using MF by specialists to establish long-distance telephone calls, dual-tone multi-frequency signaling was developed for end-user signaling without the assistance of operators.
The DTMF system uses two sets of four frequencies in the voice frequency range transmitted in pairs to represent sixteen signals, representing the ten digits and six additional signals identified as the letters A to D, and the symbols # and *. As the signals are audible tones, they can be transmitted through line repeaters and amplifiers, and over radio and microwave links.
AT&T described the product as "a method for pushbutton signaling from customer stations using the voice transmission path". To prevent consumer telephones from interfering with the MF-based routing and switching between telephone switching centers, DTMF frequencies differ from all of the pre-existing MF signaling protocols between switching centers: MF/R1, R2, CCS4, CCS5, and others that were later replaced by SS7 digital signaling. DTMF was known throughout the Bell System by the trademark Touch-Tone. The term was first used by AT&T in commerce on July 5, 1960, and was introduced to the public on November 18, 1963, when the first push-button telephone was made available to the public. As the parent company of Bell Systems, AT&T held the trademark from September 4, 1962, to March 13, 1984. It is standardized by ITU-T Recommendation Q.23.
Other vendors of compatible telephone equipment called the Touch-Tone feature tone dialing or DTMF. Automatic Electric (GTE) referred to it as "Touch-calling" in their marketing. Other trade names such as Digitone were used by the Northern Electric Company in Canada.
As a method of in-band signaling, DTMF signals were also used by cable television broadcasters as cue tones to indicate the start and stop times of local commercial insertion points during station breaks for the benefit of cable companies. Until out-of-band signaling equipment was developed in the 1990s, fast, unacknowledged DTMF tone sequences could be heard during the commercial breaks of cable channels in the United States and elsewhere.[citation needed] Previously, terrestrial television stations used DTMF tones to control remote transmitters. In IP telephony, DTMF signals can also be delivered as either in-band or out-of-band tones, or even as a part of signaling protocols, as long as both endpoints agree on a common approach to adopt.