Help


[permalink] [id link]
+
Page "Dual-tone multi-frequency signaling" ¶ 16
from Wikipedia
Edit
Promote Demote Fragment Fix

Some Related Sentences

DTMF and tones
As a method of in-band signaling, DTMF tones were also used by cable television broadcasters to indicate the start and stop times of local commercial insertion points during station breaks for the benefit of cable companies.
Previously, terrestrial television stations also used DTMF tones to shut off and turn on remote transmitters.
DTMF signaling tones can also be heard at the start or end of some VHS ( Video Home System ) cassette tapes.
DTMF tones are sometimes used in caller ID systems to transfer the caller ID information, however in the USA only Bell 202 modulated FSK signaling is used to transfer the data.
This means that two subsequent DTMF tones are enough to transfer whole byte of data or 8-bit ASCII character.
Normally, a PBX is connected via a T1 with robbed bit signaling to indicate on-hook or off-hook conditions and MF and DTMF tones to encode the destination number.
The keys control a tone generator circuit ( not shown ) that makes DTMF tones that the exchange receives.
* Specialized Resource Function ( SRF ) or Intelligent Peripheral ( IP ) This is a node which can connect to both the SSP and the SCP and delivers additional special resources into the call, mostly related to voice data, for example play voice announcements or collect DTMF tones from the user.
In practice, the best trade-off is between complexity 2 and 4, though higher settings are often useful when encoding non-speech sounds like DTMF tones, or if encoding is not in real-time.
Such key-locked telephones, if wired to a modern DTMF capable exchange, can also be exploited by a tone dialer that generates the DTMF tones used by modern keypad units.
Music or tones such as DTMF or fax tones cannot be transported reliably with this codec, and thus some other method such as G. 711 or out-of-band methods should be used to transport these signals.
Interactive voice response ( IVR ) is a technology that allows a computer to interact with humans through the use of voice and DTMF tones input via keypad.
DTMF telephones enabled the use of in-band signaling, i. e., they transmit audible tones in the same 300 Hz to 3. 4 kHz range occupied by the human voice.
DTMF tones are entered via the telephone keypad.
However, if the call was to be placed with precedence, a key in the rarely used and rarely seen 1633 Hz column of DTMF tones would be pressed before dialing to assign this:
One variant, targeted at children too young to dial a number, enticed children to hold the phone up to the television set while the DTMF tones of the number were played.
As computers benefit of a full keyboard, the developers felt that it was more natural to allow typing DTMF tones by using the computer keyboard while in a middle of an audio session without having to present the end-user an explicit dial-pad graphical user interface.
Users with a transceiver capable of producing touch tones ( DTMF signals ) can make a telephone call, typically limited by settings in the autopatch module to be only to toll-free numbers, such as local calls or toll-free numbers.
In telecommunications, in-band signaling is the sending of metadata and control information within the same band or channel used for voice ( e. g. DTMF tones ) and can be heard by the callers, as opposed to out-of-band signals ( e. g. SS7 control signals ) which cannot be heard as they are on a different channel or band.
For example, when dialing a modern telephone, the telephone number is encoded and transmitted across the telephone line as Dual-Tone Multi-Frequency ( DTMF ) tones.
As a method of in-band signaling, DTMF tones were also used by cable television broadcasters to indicate the start and stop times of local insertion points during station breaks for the benefit of cable companies.
DTMF signaling in the cable industry went away because it was distracting to viewers, it was susceptible to interference when DTMF tones were sounded by characters in television shows ( a character dialing a Touch-Tone telephone in a television show might convince the cable company computers to switch away from a " hot feed " to dead air ), and the cost of human-imperceptible signaling technologies decreased.

DTMF and are
Commonly used are DTMF broadcasts over phone lines ( direct connection or standard PSTN ) or over radio broadcast.
DTMF decoding and speech recognition are used to interpret the caller's response to voice prompts.
Media streaming functions such as echo cancellation, DTMF, and tone sender are also located in the media gateway.
Amateur radio ( or ham ) operators within radio range of a local node are able to use DTMF tone generators to initiate a node-to-node connection with any other available node in the world.
Two chips are needed because the MT8870 has latched outputs, and the IRLP software looks for short pulses at the parallel port pins 10, 12, 13, 15 in order to acknowledge a DTMF digit.
There are several ways of achieving this, including Dual Tone Multiple Frequency ( DTMF ) signalling and Continuous Tone Coded Squelch System ( CTCSS ).
Base stations must be located sufficiently far apart so that interference is not experienced, and also selective calling techniques such as CTCSS and DTMF are used to ensure that as many mobiles as possible can use a given channel.
Sometimes Knox Boxes are linked via radio to the dispatch station, where the dispatcher can release the keys with DTMF tones.
Symbols in the DTMF and MF alphabets are sent as tone pairs ; DTMF selects one tone from a " high " group and one from a " low " group, while MF selects its two tones from a common set.

DTMF and also
It's also possible to transfer Binary code ( including ASCII text messages ) using DTMF by treating received code as hexadecimal interpretation of nibble, assuming that E is equal to * and F is equal to #.
* Dual-tone multi-frequency ( DTMF, also called Touch Tone )
Most fixed-line phones now use dual tone multi frequency ( DTMF, also called touch tone or tone dialing ), supported by push-button telephones, rather than pulse dialing, but most telephone equipment retains support for pulse dialing for backward compatibility.
Some units ( especially amateur HTs ) also include DTMF keypads for remote operation of various devices such as repeaters.
It also added DTMF tone dialing for the internal modem, where the Model 100 only supported pulse dialing.

DTMF and used
Dual-tone multi-frequency signaling ( DTMF ) is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center.
The version of DTMF that is used in push-button telephones for tone dialing is known as Touch-Tone.
DTMF, as used in push-button telephone tone dialing, was known throughout the Bell System by the trademark Touch-Tone.
Other vendors of compatible telephone equipment called the Touch-Tone feature Tone dialing or DTMF, or used their own registered trade names such as the Digitone of Northern Electric ( now known as Nortel Networks ).
An example is dual-tone multi-frequency signaling ( DTMF ), which is used on most telephone lines to customer premises.
It is notable that the two methods can be combined: Even if the exchange does not support DTMF, the key lock can be circumvented by switch-hooking, and the tone dialer can be then used to operate automated DTMF controlled services that can't be used with rotary dial.
A silver box is a modified DTMF keypad that adds the four additional keys used in the now-obsolete autovon phone system.
The DTMF ANI or caller ID from the callbox will be used to display callbox sign number and location on the CAD system.
MF was used for signaling in trunking applications, and is a precursor of modern DTMF signaling ( TouchTone ) now used for subscriber signalling.

0.095 seconds.