• DTMF
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Integrated Services Digital Network Consumer and industry perspectives
1
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
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Modulation - List of common digital modulation techniques
1
Dual-tone multi-frequency
(DTMF)
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History of mobile phones - Radio Common Carrier
1
Other systems used DTMF
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History of mobile phones - Emergence of automated services
1
This was a push-button telephone, and
used transistors and DTMF signaling
to improve its operational reliability
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Payment Card Industry Data Security Standard - PCI compliance in call centers
1
The DTMF tones are converted to
monotones so the agent cannot
recognize them and so that they
cannot be recorded
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Real-time Transport Protocol - Profiles and Payload formats
1
The profile defines the codecs used to
encode the payload data and their
mapping to payload format codes in the
Payload Type (PT) field of the RTP
header . Each profile is accompanied by
several payload format specifications,
each of which describes the transport of
a particular encoded data. The audio
payload formats include G.711, G.723,
G.726, G.729, GSM, QCELP, MP3, and
DTMF, and the video payload formats
include H.261, H.263, H.264, and MPEGhttps://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html
Telephone exchange - Historic perspective
1
Exchanges based on the Strowger switch
were eventually challenged by other
exchange types and later by crossbar
technology. These exchange designs
promised faster switching and would
accept pulses faster than the Strowger's
typical 10 pps—typically about 20 pps. At
a later date many also accepted DTMF
"touch tones" or other tone signaling
systems.
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Telephone exchange - Historic perspective
1
A transitional technology (from pulse to
DTMF) had DTMF link finders which
converted DTMF to pulse, to feed to older
Strowger, panel, or crossbar switches.
This technology was used as late as mid2002.
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Telephone exchange - Early automatic exchanges
1
The telephone exchange automatically
senses an off-hook condition on the
telephone when the user removes a
handset from the switchhook and
provides dial tone to that phone to
indicate to the user that the exchange is
ready to receive dialed digits. The pulses
or DTMF tones generated by the
telephone are processed and a
connection is established to the called
telephone within the same exchange or
to another distant exchange.
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Telephone exchange - Electromechanical signaling
1
In Bell System trunks, it was common to
use 20 pulse-per-second between
crossbar switches and crossbar tandems.
This was twice the rate of Western
Electric/Bell System telephone dials. Using
the faster pulsing rate made trunk
utilization more efficient because the
switch spent half as long listening to digits.
DTMF was not used for trunk signaling.
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Telephone exchange - Electromechanical signaling
1
Multi-frequency (MF) was the last of the predigital methods. It used a different set of
tones sent in pairs like DTMF. Dialing was
preceded by a special keypulse (KP) signal
and followed by a start (ST). Variations of the
Bell System MF tone scheme became a
CCITT standard. Similar schemes were used
in the Americas and in some European
countries including Spain. Digit strings
between switches were often abbreviated to
further improve utilization.
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Telecom switch - Historic perspective
Exchanges based on the Strowger
switch were eventually challenged by
Panel switch|other exchange types
and later by Crossbar switch|crossbar
technology. These exchange designs
promised faster switching and would
accept pulses faster than the
Strowger's typical 10 pps—typically
about 20 pps. At a later date many also
accepted DTMF touch tones or other
tone signaling systems.
1
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Telecom switch - Electromechanical signaling
1
Multi-frequency|Multi-frequency (MF) was
the last of the pre-digital methods. It used
a different set of tones sent in pairs like
DTMF. Dialing was preceded by a special
keypulse (KP) signal and followed by a
start (ST). Variations of the Bell System
MF tone scheme became a ITU-T|CCITT
standard. Similar schemes were used in
the Americas and in some European
countries including Spain. Digit strings
between switches were often abbreviated
to further improve utilization.
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Telephone - Details of operation
1
The keys control a tone generator circuit
(not shown) that makes DTMF tones that
the exchange receives
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Interactive Voice Response
1
'Interactive voice response' ('IVR') is a
technology that allows a computer to
interact with humans through the use
of voice and dual-tone multi-frequency
signaling|DTMF tones input via keypad.
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Interactive Voice Response - History
1
DTMF telephones enabled the use of inband signaling, i.e., they transmit audible
tones in the same 300Hz to 3.4kHz range
occupied by the human voice
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Interactive Voice Response - History
The mature technology allowed
clusters of 96 channels of high-density
digital phone interface gear
(terminating four T1 lines of twenty
four channels each) to each be
controlled by one application
processor, running individual
applications, one per channel,
accepting DTMF touch tone inputs,
accessing a large stored vocabulary
for output, recording and playing back
user speech when necessary.
1
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Interactive Voice Response - History
1
With improvements in technology, systems
could use speaker-independent voice
recognition of a limited vocabulary instead
of requiring the person to use DTMF
signaling.
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Interactive Voice Response - Technologies used
1
DTMF decoding and speech recognition
are used to interpret the caller's response
to voice prompts. DTMF tones are entered
via the telephone keypad.
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Interactive Voice Response - Technologies used
In telecommunications, an 'audio
response unit' (ARU) is a device that
provides synthesized voice responses
to DTMF keypresses by processing
calls based on (a) the call-originator
input, (b) information received from a
database, and (c) information in the
incoming call, such as the time of day.
1
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Mobile radio telephone - Radio Common Carrier
1
Other systems used
DTMF
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Media server - Media Servers in Telephony
1
Conferencing servers may also need
other specialized functions like
loudest talker detection, or
Transcode|transcoding of audio
streams, and also interpreting DTMF
tones used to navigate menus
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Area code - History
1
Such numbering strategies became
less important when the Bell System
introduced Dual-tone multi-frequency
(DTMF) signaling in its TouchTonereg; service starting in 1963,
where all digits were generated in the
same amount of time.
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1-1-2 - Origins
Additionally, telephone systems used
pulse dialling instead of later DTMF tones;
briefly activating the hook once has the
same effect as dialling 1, so repeatedly
pushing the hook might result in calling 11-1
1
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Nokia Lumia 800 - Diagnostic Tool
1
On this diagnostic tool, a user can run
tests on the following: Accelerometer,
ALS, audio loopback, camera, battery
status, DTMF, gyroscope, hardware
buttons, headset detection, LCD white,
lights, life timer, magnetometer, power
source, proximity, speaker, touch and
vibration. It's also possible to perform
all the tests in one run.
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ISDN - Consumer and industry perspectives
1
Normally, a PBX is connected via a T1
with robbed bit signaling to indicate onhook or off-hook conditions and Multifrequency|MF and Dual-tone multifrequency|DTMF tones to encode the
destination number
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Improved Mobile Telephone Service - Terminal
These were essentially modified
walkie-talkies with a DTMF (dual tone
multi-frequency) keypad attached on
the front panel, which fooled the
terminal into believing an IMTS
mobile was using the system
1
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Intelligent network service - SS7 architecture
1
* '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.
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Speex - Features
1
In practice, the best trade-off is between
complexity 2 and
4,[http://www.speex.org/docs/manual/spee
xmanual/node4.html#SECTION004140000
00000000000 Codec Description] though
higher settings are often useful when
encoding non-speech sounds like DTMF
tones, or if encoding is not in real-time.
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Premium-rate telephone number
1
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
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Nokia Lumia 900 - Diagnostic Tool
1
On this diagnostic tool a user can run
tests on the following: Accelerometer,
ALS, audio loopback, camera, battery
status, DTMF, gyroscope, hardware
buttons, headset detection, LCD
white, lights, life timer,
magnetometer, power source,
proximity, speaker, touch and
vibration. It's also possible to perform
all the tests in one run.
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WebRTC - Design
As of March 2012 the IETF WebRTC
Codec and Media Processing
Requirements draft requires
implementations to provide PCMA/PCMU
(RFC 3551), Telephone Event as DTMF
(RFC 4733), and Opus (audio
format)|Opus (RFC 6716), along with a
number of video codec minimum
capabilities. The Peerconnection, Data
channels and a media capture browser
1
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G.729
Dual-tone multi-frequency signaling
(DTMF), fax transmissions, and highquality audio cannot be transported
reliably with this codec. DTMF requires the
use of the RTP Payload for DTMF Digits,
Telephony Tones, and Telephony Signals
as specified in RFC 2833.
1
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Nuance Communications - Nuance history prior to the 2005 merger with ScanSoft
designing and developing speech
solutions requires a different skill-set
and mind-set to that of traditional
DTMF solutions.
1
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Pager - History
1
The Bell System Bellboy radio pagers
each used three tuned reed receiver
relays, each relay tuned to one of 33
different frequencies, selectively
ringing a particular customer when
all three relays were activated at the
same time -- a precursor of DTMF.
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Modulator - List of common digital modulation techniques
1
**Dual-tone multi-frequency
(DTMF)
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PCI DSS - PCI compliance in call centers
The Dual-tone multi-frequency
signaling|DTMF tones are converted
to monotones so the agent cannot
recognize them and so that they
cannot be recorded
1
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Phreaking - Switch hook and tone dialer
1
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.
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Jingle (protocol) - Clients supporting Jingle
1
* Yate (telephony engine)|Yate/YateClient
supports Jingle in both client and server
mode, audio and file transfer, also call
transfer and DTMF.
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Jitsi - Features
* Dual-tone multi-frequency
signaling|DTMF support with SIP INFO,
Real-time Transport Protocol|RTP (RFC
2833/RFC 4733), In-band
1
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Voice browser
A voice browser presents information
aurally, using pre-recorded audio file
playback or text-to-speech synthesis
software. A voice browser obtains
information using speech recognition and
keypad entry, such as DTMF detection.
1
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Microsoft Speech Server
1
The 'Microsoft Speech Server' is a product
from Microsoft designed to allow the
authoring and deployment of Interactive
voice response|IVR applications
incorporating Speech Recognition, Speech
Synthesis and Dual-tone multifrequency|DTMF.
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Dual-tone multi-frequency signaling
1
DTMF is standardized by ITU-T Recommendation
[http://www.itu.int/rec/T-REC-Q.23/en Q.23]
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Dual-tone multi-frequency signaling - Multifrequency signaling
Prior to the development of DTMF,
numbers were dialed on automated
telephone systems by means of pulse
dialing (dial pulse, DP, in the United
States|U.S.) or loop disconnect (LD)
signaling, which functions by rapidly
disconnecting and re-connecting the
calling party's telephone line, similar
to flicking a light switch on and off
1
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Dual-tone multi-frequency signaling - Multifrequency signaling
1
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).
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Dual-tone multi-frequency signaling - Multifrequency signaling
1
The DTMF system uses eight different
frequency signals transmitted in pairs to
represent 16 different numbers, symbols
and letters - as detailed below.
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Dual-tone multi-frequency signaling - Multifrequency signaling
1
As a method of in-band signaling, DTMF
tones were also used by cable television
Broadcasting|broadcasters to indicate the
start and stop times of local commercial
insertion points during station breaks for
the benefit of cable companies. Until better
out-of-band signaling equipment was
developed in the 1990s, fast,
unacknowledged, and loud DTMF tone
sequences could be heard during the
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Dual-tone multi-frequency signaling - Multifrequency signaling
1
Based on this prior success with using MF
by specialists to establish long-distance
telephone calls, Dual-tone multi-frequency
(DTMF) signaling was developed for the
consumer to signal their own telephonecall's destination telephone number
instead of talking to a telephone operator.
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Dual-tone multi-frequency signaling - Multifrequency signaling
1
DTMF, as used in push-button telephone
tone dialing, was known throughout the
Bell System by the trademark Touch-Tone
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Dual-tone multi-frequency signaling - Multifrequency signaling
Multi-frequency signaling is a
precursor of modern DTMF signaling
(TouchTone), now used for subscriber
signalling. DTMF uses eight
frequencies.
1
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Dual-tone multi-frequency signaling - #, *, A, B, C, and D
1
DTMF tones are also used by some cable
television networks and radio networks to
signal the local cable company/network
station to insert a local advertisement or
station identification. These tones were
often heard during a station ID preceding a
local ad insert. Previously, terrestrial
television stations also used DTMF tones
to shut off and turn on remote transmitters.
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Dual-tone multi-frequency signaling - #, *, A, B, C, and D
1
DTMF signaling tones can also be heard
at the start or end of some VHS (Video
Home System) cassette tapes. Information
on the master version of the video tape is
encoded in the DTMF tone. The encoded
tone provides information to automatic
duplication machines, such as format,
duration and volume levels, in order to
replicate the original video as closely as
possible.
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Dual-tone multi-frequency signaling - #, *, A, B, C, and D
DTMF tones are sometimes used in
caller ID systems to transfer the caller
ID information, but in the United
States only Bell 202 modem|Bell 202
modulated Frequency-shift
keying|FSK signaling is used to
transfer the data.
1
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Dual-tone multi-frequency signaling - Keypad
1
The DTMF keypad is laid out in a 4times;4
matrix in which each row represents a low
frequency and each column represents a
high frequency. Pressing a single key sends
a sinusoidal tone for each of the two
frequencies. For example, the key 1
produces a superimposition of tones of 697
and 1209 hertz (Hz). Initial pushbutton
designs employed levers, so that each button
activated two contacts. The tones are
decoded by the switching center to determine
the keys pressed by the user.
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Dual-tone multi-frequency signaling - Special tone frequencies
1
As with other multi-frequency receivers,
DTMF was originally decoded by tuned
filter banks. Late in the 20th century most
were replaced with digital signal
processors. Although DTMF can be
decoded using any frequency domain
transform (such as the popular Fast
Fourier transform), the Goertzel algorithm
is a common algorithm to consider due to
its high performance for DTMF.
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Sign-on - Sign-on sequence
1
# A signal to turn on remote transmitters
may be played—this is usually a series of
DTMF|touch tones.
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Softphone - Features
A typical softphone has all standard
telephony features (DND, Mute, Dual-tone
multi-frequency|DTMF, Flash, Hold,
Transfer etc.) and often additional features
typical for online messaging, such as user
presence indication, video, wide-band
audio. Softphones provide a variety of
audio codecs, a typical minimum set is
G.711 and G.729.
1
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Western Electric - Technological innovations
1
DTMF was generally
referred to by the
trademarked name,
Touch-Tone.
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Ekiga - Technical features
1
* Dual-tone multifrequency|DTMF
support (SIP and
H.323)
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Caller ID - Operation
Instead of sending the caller ID in
between the first and second ring,
some systems use a line reversal to
announce the caller ID, or caller ID
signals are simply sent without any
announcement. Instead of Bell 202,
the European alternative V.23 is
sometimes used, (without the 75-baud
reverse channel) or the data is sent
using DTMF signalling.
1
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Caller ID - Notes
Some providers use
frequency-shift keying|FSK,
others use the DTMF
protocol.
1
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✆
Until approximately the 1970s most
telephones used a rotary dial, which was
superseded by the modern Dual-tone
multi-frequency signaling|DTMF pushbutton dial, first introduced by ATT in
1963.Dodd, Annabel Z., The Essential
Guide to Telecommunications
1
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List of algorithms - Digital signal processing
1
* Goertzel algorithm: identify a particular
frequency component in a signal. Can be
used for DTMF digit decoding.
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Push-button telephone
1
On 18 November 1963 the Bell System in
the United States officially introduced dualtone multi-frequency (DTMF) technology
under its registered Touch-Tone® mark
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Push-button telephone
1
Although DTMF was the driving technology
implemented in push-button telephones,
some telephone manufacturers used pushbutton keypads to generate pulse dial
signaling. Before the introduction of TouchTone telephone sets, the Bell System
sometimes used the term push-button
telephone to refer to key system telephones,
which were rotary dial telephones that also
had a set of push-buttons to select one of
multiple telephone circuits, or to activate
other features.
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Push-button telephone - Touch-Tone
The international standard for
telephone signaling utilizes dual-tone
multi-frequency (DTMF) signaling,
more commonly known as Touch-Tone
dialing
1
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Push-button telephone - Touch-Tone
The Touch-Tone system uses audible
tones for each of the digits zero through
nine. Later this was expanded by two keys
labeled with an asterisk (*) and the pound
or hash sign (#) to represent the 11th and
12th DTMF signals. These signals
accommodate various additional services
and customer-controlled calling
features.[http://www.greatachievements.or
g/?id=3625 Great AchievementsTelephone Timeline]
1
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Push-button telephone - Touch-Tone
1
The DTMF standard assigns specific
frequencies to each column and row of
push-buttons in the telephone keypad;
the columns in the push-button pad
have higher-frequency tones, and
rows have lower-frequency tones in
the audible range. When a button is
pressed the dial generates a
combination signal of the two
frequencies for the selected row and
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Push-button telephone - Touch-Tone
1
When announced, the DTMF technology was not
immediately available on all switching systems
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Push-button telephone - Touch-Tone
1
While a tone-to-pulse converter could
be deployed to any existing
mechanical office line using 1970s
technology, its speed would be limited
to pulse dialling
rates.[http://rbsfm.org/Downloads/A
PPNOTE/DTMF/MSAN-108.PDF Mitel
Application note MSAN-108]:
Applications of the MT8870 integrated
DTMF receiver, Page A50, Figure 2
(MT8870 DTMF receiver, MT4325
Pulse dialler), June 1983
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Push-button telephone - DTMF keypad layout
1
This research resulted in the design of the
DTMF keypad that arranged the pushbuttons into 12 positions in a 3-by-4
position rectangular array, and placed the
1, 2, and 3 keys in the top row for most
accurate dialing
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Push-button telephone - DTMF keypad layout
The DTMF keyboard layout broke with the
tradition established in cash registers (and
later adopted in calculators and computers) of
having the 0 key at the bottom and the
remaining keys increasing in rows
above.[http://www.straightdope.com/columns/r
ead/2019/why-do-telephone-keypads-countfrom-the-top-down-while-calculators-countfrom-the-bottom-up Why do telephone
keypads count from the top down, while
calculators count from the bottom up?] This
was due to research conducted by Bell Labs
using test subjects unfamiliar with keypads
1
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Push-button telephone - Pulse dialing
1
Historically, not all push-button telephones
used DTMF dialing technology. Some
manufacturers implemented pulse dialing
with push-button keypads and even Western
Electric produced several telephone models
with a push-button keypad that could also
emit traditional dial pulses. Sometimes the
mode was user-selectable with a switch on
the telephone. Pulse mode push-button
keypads typically stored the dialed number
sequence in a digit collector register to permit
rapid dialing for the user.
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Push-button telephone - Features
Most analog telephone adapters for
Internet-based telecommunications (VoIP)
recognise and translate DTMF tones but
ignore dial pulses, an issue which also
exists for some Private branch
exchange|PBX systems. Like cellular
handsets, telephones designed for voiceover-IP use out-of-band signalling to send
the dialled number.
1
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Automated attendant - Feature Description
1
Callers who have a touch tone (DTMF)
phone can dial an extension number or, in
most cases, wait for operator (attendant)
assistance
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Amateur radio repeater - Repeater networks
1
This feature is typically done with DTMF tones
to control the network infrastructure
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Professional Mobile Radio - Introduction
1
When private- or professional-mobile-radio
(PMR) first started the systems simply
consisted of a single base station with a
number of mobiles that could
communicate with this single base station.
These systems are still in widespread use
today with taxi firms and many others
using them for communication. Now
facilities such as DTMF and CTCSS
provide additional calling selection.
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Professional Mobile Radio - Selective calling
1
Many systems operate with the remote or
mobile stations being able to hear all the
calls being made. This may not always be
satisfactory and a system of selective
calling may be required. There are several
ways of achieving this, including Dual
Tone Multiple Frequency (DTMF)
signalling and Continuous Tone Coded
Squelch System (CTCSS).
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Professional Mobile Radio - Selective calling
1
DTMF is a system that is widely used for
telephone signalling and is almost
universally used for touch tone dialing for
landline telephones today. It uses set pairs
of tones that are used to carry the
information. The eight frequencies used
are 697, 770, 852, 941 Hz which are
termed the low tones and 1209, 1336,
1477, and 1633 Hz which are high tones.
One high and one low tone is used
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Professional Mobile Radio - Selective calling
1
The disadvantage of this system is
that if the receiver does not pick up
the code at the instant the DTMF
signalling takes place then it will not
respond to any of the message
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Professional Mobile Radio - Modulation
1
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.
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Signaling (telecommunications) - In-band and out-of-band signaling
In the public switched telephone
network (PSTN), in-band signaling is
the exchange of call control
information within the same channel
that the telephone call itself is using.
An example is dual-tone multifrequency signaling (DTMF), which is
used on most telephone lines to
customer premises.
1
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Signaling (telecommunications) - Line versus register signaling
1
Finally, starting in the second half of the century,
address signaling is by DTMF.
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Signaling (telecommunications) - Classification
1
*E and M signaling (EM) is an out-ofband channel-associated signaling
system. The base system is intended
for line signaling, but if decadic
pulses are used it can also convey
register information. EM line
signaling is however usually paired
with DTMF register signaling.
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In-band signaling
In telecommunications, 'in-band
signaling' is the sending of metadata
and control signal|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.
Signalling System No. 7|SS7 control
signals) which cannot be heard as they
are on a different channel or band.
1
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In-band signaling - Telephone
1
For example, when dialing from a land-line
telephone, the telephone number is
encoded and transmitted across the
telephone line in form of dual-tone multifrequency signaling (DTMF)
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In-band signaling - Non-telephone
1
As a method of in-band signaling, DTMF
tones were also used by cable television
Broadcasting|broadcasters to indicate the
start and stop times of local insertion
points during station breaks for the benefit
of cable companies. Until better, out-ofband signaling equipment was developed
in the 1990s, fast, unacknowledged, and
loud DTMF tone sequences could be
heard during the commercial breaks of
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In-band signaling - Non-telephone
1
These DTMF sequences were sent by
the originating cable network's
equipment at the uplink satellite facility,
and were decoded by equipment at
local cable companies. A specific tone
sequence indicated the exact time that
the feeds should be switched to and
away from the master control feed, to
locally-broadcast commercials.
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In-band signaling - Non-telephone
1
An example of a cable company DTMF
sequence code would communicate the
following to the cable company's
broadcast equipment:
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In-band signaling - Non-telephone
1
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.
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Fantasy football (American) - History
1
Trading and other game interactions took place
via DTMF (touchtone) phone technologies
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Auto dialer - Modem versus telephony boards
1
Traditional advantages of using telephony
cards over simple modems include
detecting DTMF|touch tones and
transferring calls directly through to the
caller.
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Audio Messaging Interchange Specification - Technical background
1
AMIS is completely in-band and analog,
meaning that the control commands to
indicate who the message is from, the time
received and from mailbox or caller ID
information is all sent as a series of DTMF
(Touch tone) digits - along with the
message itself, which is transmitted
(played and re-recorded by the target
system) in real time.
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Multi-frequency shift keying - 2-tone MFSK
It is possible to combine two MFSK
systems to increase the throughput of
the link. Perhaps the most widely used
2-tone MFSK system is dual-tone
multi-frequency (DTMF), better
known by its ATT trademark of Touch
Tone. Another is the Multi-frequency
(MF) scheme used during the 20th
century for in-band signalling on
trunks between telephone exchanges.
1
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Multi-frequency shift keying - 2-tone MFSK
1
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 MF use
different tone frequencies largely to keep
end users from interfering with inter-office
signaling. In the 1970s, MF began to be
replaced by digital out-of-band signaling,
a conversion motivated in part by the
widespread fraudulent use of MF signals
by end users known as phone phreaks.
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Multi-frequency shift keying - VHF UHF communications
DTMF was initially developed for
telephone line signaling. It is frequently
used for telecommand (remote control)
applications over VHF and UHF voice
channels.
1
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Voiceportal
In telecommunications circles, Voice
portals may be referred to as Interactive
Voice Response (IVR) systems, but this
term also includes DTMF services.
1
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Telephone banking - Operation
To access telephone banking, the
customer would call the special phone
number set up by the financial
institution. The service can be
provided using an automated system,
using speech recognition and Dualtone multi-frequency signaling|DTMF
technology or by live customer service
representatives.
1
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Line card
1
In some telephone exchange designs, the
line cards generate ringing
(telephony)|ringing current and decode
DTMF signals
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Broadcast automation - Early analog systems
Satellite programming often used
audible dual-tone multi-frequency
(DTMF) signals to trigger events at
affiliate stations. This allowed the
automatic local insertion of ads and
station IDs. Because there are 12 (or
16) tone pairs, and typically four tones
were sent in rapid succession (less
than one second), more events could
be triggered than by sub-audible tones
1
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Walkie-talkie - Contemporary use
1
Some units (especially amateur HTs)
also include DTMF keypads for remote
operation of various devices such as
repeaters
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Switching center - Early automatic exchanges
A telephone exchange automatically
senses an off-hook condition of the
telephone when the user removes the
handset from the switchhook or cradle.
The exchange provides dial tone at that
time to indicate to the user that the
exchange is ready to receive dialed
digits. The pulses or DTMF tones
generated by the telephone are
processed and a connection is
established to the destination telephone
within the same exchange or to another
1
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G.723.1 - Use
G.723.1 is mostly used in Voice over IP
(VoIP) applications due to its low
bandwidth requirement. 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 signaling|out-of-band methods
should be used to transport these signals.
The complexity of the algorithm is below
16 MIPS. 2.2 kilobytes of RAM is needed
for codebooks.
1
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Voice-based marketing automation - Functionality
'Hosted IVR' (interactive voice
response) is a Cloud
computing|cloud-based technology
that allows a computer to interact with
humans through the use of voice and
Dual-tone multi-frequency
signaling|DTMF tones input via
keypad
1
•
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Centrex - Birth of Centrex
1
Among other changes, the Phase 3 consoles used
DTMF rather than multifrequency pulsing
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Telephone keypad
1
The contemporary keypad is laid out
in a 4times;3 grid, although the
original dual-tone multifrequency|DTMF system in the new
keypad had an additional column for
four now-defunct menu selector keys
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Telephone keypad - Letter mapping
1
On certain BlackBerry devices, a user
can press the Alt key, followed by the
desired letter, and the device will
generate the appropriate DTMF
tone.[http://www.pctoday.com/editori
al/article.asp?article=articles%2F200
5%2Ft0310%2F35t10%2F35t10.asp
Blackberry Tips], PC World, October
2005.
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Loop around
1
*Using uncommon DTMF tones (A
through D) in the telephone number
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Sign-off - Sign-off sequence
1
# A signal to turn off remote transmitters
may be played—this is usually a series of
DTMF|touch tones. Once the transmission
has been cut off there will usually only be
Noise (video)|video static on television
stations or Noise (radio)|radio static on
radio stations.
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D-STAR - Criticisms
1
With P25 designed for Govt and Federal
Emergency use, it lacks Amateurcentric features for example, P25
amateur radio implementations do not
use call sign routing, and they cannot
control linked reflectors or repeaters
but do have DTMF, telegrams, phone
patch, MDC1200, TMS messaging, any
many more signalling facilities,
including several advanced security
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Civil defense siren - Sirens in integrated public warning systems
1
Commonly used are DTMF broadcasts
over phone lines (direct connection or
standard PSTN) or over radio broadcast
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Pulse dialing - Successor technologies
1
In 1963 the Bell System introduced
dual-tone multi-frequency (DTMF)
technology under the name TouchTone (a trademark in the U.S
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Quik Call I
1
Selective calling is akin to the use of a
lock on a door. A radio with carrier
squelch is unlocked and will let any
signal in. Selective calling locks out
all signals except ones with the
correct 'key', in this case a specific
digital code. Selective calling systems
can overlap; a radio may have (group
call) and DTMF individual calling.
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Savage Love - Other abbreviations
'DTMFA': Dump The Mother-Fucker
Already (used at a closing of a response to
indicate that immediately ending the
writer's abusive or worthless relationship is
advised).
1
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Nokia 8810 - Calls
The phone featured the ability to make
conference calls, hold calls and send DTMF
tones
1
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History of The Weather Channel - The Live By It era: June 2001–August 2005
The Weather Star III was also
discontinued from service as it did not
meet DTMF tone and weather warning
regulations
1
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Hendrik van Rheede - Biography
1
They visited Simon van der Stel in Cape of Good Hope, and
Groot Constantia; the area Drakenstein Local
Municipality|Groot Drakenstein was named after
him.[http://www.heritagesa.org/index.php?option=com_content
view=articleid=61:a-different-history-of-franschoek-and-thedrakenstein-district-submitted-by-alan-montgomery-march2010catid=6:latest-news A DIFFERENT HISTORY OF
FRANSCHOEK and the DRAKENSTEIN DISTRICT] Van Rheede
recommended measures for forestry and
viniculture.[http://books.google.nl/books?id=UddDDtMF20Cpg=PA70lpg=PA70dq=Hendrik+van+Rheede+Dra
kensteinsource=blots=DM4wpanlQnsig=wpdGJ69G4jwwad3_J
XXrnKdMvIUhl=enei=CwgfTZqGBoWx8gO715yXBQsa=Xoi=boo
k_resultct=resultresnum=6ved=0CDAQ6AEwBTgK#v=onepage
qf=false New Scientist 25 Jun 1987] In 1687 Governor Van der
Stel opened this region to
farmers.[http://www.tanap.net/content/activities/documents/res
olutions_Cape_of_Good_Hope/introduction_english/39.htm
Intro (English) to the Resolutions of Cape of Good Hope /
Places named after members of the Council of Policy]
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Blue box - Frequencies and timings
1
This set of MF tones was originally devised
for Bell System switchboard operator|longdistance operators placing calls manually and
predates the 1963 DTMF Touch-Tone system
used by subscribers; in some 1950s and
1960s ATamp;T archive films, operators are
shown asking callers for the number and
pressing KP + area code + seven-digit
number + ST manually to complete individual
toll calls. The leading 1- trunk prefix was not
dialled as the operator was already on a Long
Lines trunk at this point.
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Disney's Fantillusion
1
It features Float (parade)|floats and live
performers covered in thousands of
electronically controlled lights and a
synchronized soundtrack controlled by
a Dual-tone multi-frequency signaling
(DTMF) tone broadcast along the
parade route
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Telephone interpreting - Access
* 'Automated': an Interactive voice
response|Interactive Voice Response
(IVR) application is employed to
convert spoken or keyed Dual-tone
multi-frequency|Dual Tone Multi
Frequency (DTMF) data into a request
for connecting to an interpreter in a
specific language (identified by
Language code|unique languagecodes)
1
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History of the Israeli–Palestinian conflict - 1947-1948 war: Yishuv Vs Palestinian Arabs
and volunteers
1
[http://books.google.com/books?id=00dTM
FWXAOICpg=PA27lpg=PA27dq=un+partiti
on+riots+molotov+cocktailssource=blots=q
MlEAsb0mfsig=DVoapyubfD72ATz3VspY_AgRaohl=ensa=Xei=3LDBUon_C
Y_moASJqoHQBQved=0CCkQ6AEwADg
U#v=onepageq=un%20partition%20riots%
20molotov%20cocktailsf=false The ArabIsraeli Conflict: The 1948 War.] Google
Books'
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Scansoft - Nuance history prior to the 2005 merger with ScanSoft
designing and developing speech
solutions requires a different skill-set and
mind-set to that of traditional DTMF
solutions.
1
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Novation CAT - The Apple-CAT II
1
Several specialized applications such as
TSPS, The Cats Meow and Phantom
Access were used to mimic standard
telephone sounds such as standard
numeric DTMF dial tones as well as blue
box tones, ringing (both American and
International), dial tones, call waiting
alerts, busy signals, 2600Hz tones, and
other effects such as payphone sounds
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TuVox
1
'TuVox' is a company that produces
VXML-based telephone speechrecognition applications to replace
DTMF touch-tone systems for their
clients.
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FXO - Function
A similar FCO service provided no
difference in local calling area (the
distant exchange is in the same rate
centre). Historically, it was a means to
obtain features not available on the
local exchange (such as DTMF tone
dialling when first introduced in 1963)
or keep an existing business
telephone number operational after a
cross-town move.
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Tip and ring - Polarity
When Touch-Tone service was
introduced in the 1960s, the dual-tone
multi-frequency signaling (DTMF)
tone generator also required correct
polarity as it depended on the line
power for operation
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Model 500 telephone - Development
1
The model 1500 only had push buttons
for the 10 digits, while the model 2500
used 12 keys and included the '*' and '#'
DTMF signals to allow for extra signaling
needed in advanced service features,
such as voice response systems and call
management.
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Lineman's handset - Components
Originally, lineman's handsets
featured a rotary dial, but modern
sets use some variant of the standard
12-button Dual-tone multifrequency|DTMF Telephone
keypad|keypad
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Lineman's handset - Components
* DTMF|Tone/pulse
dialing selection switch
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Telecommunications device for the deaf - Other legacy protocols
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Other protocols used for text telephony
are European Deaf Telephone (EDT)
and Dual-tone multi-frequency
signaling (DTMF).
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