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Topic: DTMF

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	RFC 2833 (rfc2833) - RTP Payload for DTMF Digits, Telephony Tones and Tele
		DTMF digits and named telephone events are carried as part of the audio stream, and MUST use the same sequence number and time-stamp base as the regular audio channel to simplify the generation of audio waveforms at a gateway.
		In circumstances where exact timing alignment between the audio stream and the DTMF digits or other events is not important and data is sent unicast, such as the IVR example mentioned earlier, it may be preferable to use a reliable control protocol rather than RTP packets.
		DTMF digits and events are sent incrementally to avoid having the receiver wait for the completion of the event.
	www.faqs.org /rfcs/rfc2833.html (7036 words)

	DTMF
		Dual-tone-multi-frequency (DTMF, also known as touch-tone) are the audible sounds you hear when you press keys on your phone.
		It is this performance that makes DTMF ideal for clear transmission and reception in remote control (wireless or through phone lines) applications.
		The DTMF generator circuit is straight forward to construct.
	www.boondog.com /tutorials/dtmf/dtmf.htm (1720 words)

	DTMF GSM
		DTMF (Dual-tone Multi Frequency) is a tone composed of two sine waves of given frequencies.
		DTMF was not intended for data transfer; it is designed for control signals only.
		Notice that there are 16 codes; however, common DTMF dialers use only 12 of them.
	www.gsm-modem.de /dtmf-gsm.html (155 words)

	DTMF Background (Site not responding. Last check: )
		That is, a DTMF signal is one that consists of only the sum of two pure sinusoids at valid frequencies.
		In DTMF, the tone '8' is represented with the sum of 852 Hz and 1477 Hz sinusoids.
		DTMF signals that are interrupted for 10ms or less should not detect two separate signals.
	www.ece.utexas.edu /~mason/codesign/dtmf.html (357 words)

	DTMF Expalined - How it works and why it's employed as a Signalling Format.
		DTMF is actually the generic term for Touch-Tone (touch-tone is a registered trademark of ATT).
		If you are using a DTMF keypad to remotely control equipment, the tones can identify what unit you want to control, as well as which unique function you want it to perform.
		These are DTMF tones that CBS or others like them send out at the start of the broadcast to transfer (or alert to transfer) their audio onto the local affiliates airwaves.
	www.genave.com /dtmf.htm (887 words)

	DTMF Remote Control
		The purpose of this interface is to permanently monitor the Phone Line for incoming DTMF signals, output confirmation Beep’s to the line and keep the phone loop closed while the DTMF Remote is in use.
		The ground of the DTMF Remote must be floating in order to work as expected and cannot be connected to earth ground.
		The DTMF Remote is using a LCD connected to port D of the PIC for debugging purposes only.
	www.geocities.com /constantinescuradu/content/dtmf.htm (1475 words)

	DTMF Signaling
		DTMF signaling converts decimal digits (and the symbols '*' and '#') into sounds that share enough essential characteristics with voice to easily traverse circuits designed for voice.
		The DTMF coder is thus a function that maps a phone number into a voice-like signal.
		The DTMF signal for that key is the sum of two sinusoidal waves, one at each frequency.
	ptolemy.eecs.berkeley.edu /eecs20/week2/dtmf.html (453 words)

	The MathWorks - Demos - Dual-Tone Multi-Frequency (DTMF) Signal Detection
		Dual-tone Multi-Frequency (DTMF) signaling is the basis for voice communications control and is widely used worldwide in modern telephony to dial numbers and configure switchboards.
		A DTMF signal consists of the sum of two sinusoids - or tones - with frequencies taken from two mutually exclusive groups.
		The minimum duration of a DTMF signal defined by the ITU standard is 40 ms.
	www.mathworks.com /products/demos/signaltlbx/dtmf/dtmfdemo.html (1020 words)

	DTMF coder / decoder
		There are 7 digits in the dialed string and hence the waveform shows 7 distinct sub samples of the resulting DTMF encoded waveform.
		The input to the decoder is a vector containing DTMF tones that are encoded by the encoder.
		However, since I have used a band pass filter in order to decode every DTMF tone the band pass filter length can be manipulated in order to get good results in noisy environment.
	www.engr.mun.ca /~sircar/DTMF.htm (960 words)

	DTMF Basics - HW server - dtmf,basics,dual-tone multi ... (Site not responding. Last check: )
		DTMF is the basis for voice communications control.
		DTMF was designed so that it is possible to use acoustic transfer, and receive the codes using standard microphone.
		Often, dedicated integrated circuits are used, although a functional solution for DTMF transmission and receiving by a microprocessor (a PIC in most cases) exists.
	www.hw-server.com /docs/dtmfb.html (655 words)

	DTMF (Dual-Tone Multi-Frequency)
		DTMF, better known as touch-tone, is a system of signal tones used in telecommunications.
		There are twelve DTMF signals, each of which is made up of two tones from the following selection: 697 Hz, 770 Hz, 852 Hz, 941 Hz, 1209 Hz, 1336 Hz, 1477Hz.
		The tones are divided into two groups (low and high), and each DTMF signal uses one from each group.
	www.mediacollege.com /audio/tone/dtmf.html (145 words)

	GL Communications - DTMF/MF Transmit & Capture Digits
		The Capture Dialed Digits application provides the capability to capture and display DTMF and MF (along with MFR2-forward and MFR2-backward) digits and User-Defined tones as they are received on one or several time slots.
		As a part of the conversation with the other card, initially near end waits for the second card (far end) to transmit the signaling bits 1111, after which it transmits a voice input for a specified amount of time from the GL's card.
		The DTMF Transmit Dialing Digits program has no receive capability, therefore the received digits have to be assumed to occur.
	www.gl.com /dtmfmf1.html (1691 words)

	DTMF Controller for Remote Relay Control
		DTMF Remote Relay Controller The AK-16 decodes DTMF control commands received from a wired-remote such as a DTMF keypad, or a radio-remote source such as a UHF or VHF radio with a DTMF keypad.
		The DTMF inputs cause control actions including relay output control, outputting ASCII serial data, and controlling X-10 devices.
		This way, if you are not using the Morse response, and do not have the PTT line connected on your radio, you will not have to wait after each command is sent before you enter the next command.
	www.motron.com /DTMFController.html (681 words)

	DTMF Generation with Hypersignal Block Diagram- Developer Zone - National Instruments
		In addition to telephone call signaling, DTMF is becoming popular in interactive control applications, such as telephone banking or electronic mail systems, in which the user can select options from a menu by sending DTMF signals from a telephone.
		In a DTMF scheme, pairs of tones are used to signal the digits 0 through 9, pound(#), star(*), and the digits A, B, C and D. For each pair, one of the tones is selected from a low group of four frequencies, and the other from a high group of four frequencies.
		The generation of DTMF is performed as in the initial example, and the decoder example has been added, with the Test Tone Generator replaced with a sound card A/D to actually get real-time signals.
	zone.ni.com /devzone/cda/tut/p/id/3310 (1697 words)

	XEP-0181: Jingle DTMF
		The element SHOULD possess an 'action' attribute, the value of which MUST be either "button-up" or "button-down" (specifying whether the button is being depressed or released).
		The element SHOULD be sent as the payload of a Jingle session-info message as illustrated in the following example (see Protocol Namespaces regarding issuance of one or more permanent namespaces).
		Although A, B, C, and D were originally defined as part of DTMF, they were never deployed to telephony consumers and were used only for control purposes at private branch exchanges (PBXs) and central office operator stations; however, they are used in certain non-telephony applications of DTMF, such as ham radio.
	www.xmpp.org /extensions/xep-0181.html (1101 words)

	Configuring SIP DTMF Features
		DTMF dialing consists of simultaneous voice-band tones generated when a button is pressed on a telephone.
		DTMF tones are generated when a button on a touch-tone phone is pressed.
		If the duration of the DTMF event is less than the negotiated duration, the originating gateway sends an end NOTIFY message for this event with the duration field containing the exact duration of the event and the end bit set to 1.
	www.cisco.com /univercd/cc/td/doc/product/software/ios123/123cgcr/vvfax_c/callc_c/sip_c/sipc1_c/chapter8.htm (4131 words)

	Dual Tone Multi-Frequency (Touch-Tone®) Reference
		Dual Tone Multi-Frequency, or DTMF is a method for instructing a telephone switching system of the telephone number to be dialed, or to issue commands to switching systems or related telephony equipment.
		The DTMF dialing system traces its roots to a technique ATandT developed in the 1950s called MF (Multi-Frequency) which was deployed within the ATandT telephone network to direct calls between switching facilities using in-band signaling.
		The receiver must correctly detect and decode DTMF despite the presence of dial-tone, including the extreme case of dial-tone being sent by the central office at 0 dBm (which may occur in extremely long loops).
	nemesis.lonestar.org /reference/telecom/signaling/dtmf.html (1763 words)

	Intuitive Circuits, LLC. - DTMF Decoder and DTMF Encoder Products for Relay Controls
		The DTMF-8 DTMF Decoder is an inexpensive, self contained, DTMF (dual tone multiple frequency) or touch tone decoder board which permits users to remotely control, via radio or other audio producing source, the on or off state of eight devices or relays.
		Program mode: Press 2.The relay is in the on state while the corresponding DTMF tone is being received and in the off state when the DTMF tone is absent.
		The DTMF-8 DTMF Decoder is designed to control eight devices (via relays) but it is possible to control more devices by attaching multiple boards to the same incoming audio source and setting a password (more of a board ID in this case) for each board.
	www.icircuits.com /prod_dtmf8.html (604 words)

	DTMF Dial download zone
		DTMF dial is a software program designed to emit DTMF tones (including A, B, C and D) from the PC sound card.
		It has push button, keyboard, clipboard paste and command line interface - with programmable memory, last 16 number redial and tool tray operation.
		By holding the microphone of a telephone handset to the speaker this makes for a very simple and easy auto-dialer.
	www.silverstones.com /DTMFDial.html (256 words)

	Prosody application note: DTMF detection issues
		The DTMF detection on Prosody is very finely tuned in order to detect all DTMF digits within its specifications, and to reject the maximum amount of talk-off.
		Because analogue telephones reflect some of the outgoing signal, if a DTMF digit is present in the outgoing signal, it will potentially be detected by the channel which is connected to the incoming channel from the same network connection.
		When a DTMF channel is the input to a conference there will be a corresponding output channel that is connected to the same telephone.
	www.aculab.com /support/ting/an-dtmf-det-issues.html (1744 words)

	Generating DTMF tones using soundcard (Site not responding. Last check: )
		DTMF tones are the tones used in telephones for tone dialling.
		Generating DTMF tones using this method is quite easy by just summing two of theose sine waves.
		For DTMF tones 8 kHz sample rate at 8 bit resolution is well enough, but there is no problems using 16 bit resolution or higher samplerates (you just have to generate more data for that).
	users.tkk.fi /~then/mytexts/dtmf_generation.html (418 words)

	DTMF Decoder 2 by Infidigm
		The DTMF decoder 2 is a useful tool used for decoding DTMF (Dual Tone Multi frequency) generated by telephones.
		The DTMF Decoder 2 can be assembly by anyone with general electronic knowledge and soldering skills.
		If a DTMF digit is received while scrolling through EEPROM, the LCD screen is restored and the digit is appended to the end of the line.
	www.infidigm.net /projects/dtmf2 (1012 words)

	DTMF in DV mode on ID-800H
		It would be handy to be able to use DTMF for remote control purposes.
		DTMF capability for the ID-800H in DV mode might come in handy if you want to interface your D-STAR radios to IRLP or use it for phone patches.
		Phone patches are still good things to have, especially if you need to make an emergency call and the cell network is overloaded, or if you are in a fringe area for cell service.
	www.icomamerica.com /support/forums/tm.asp?m=1743 (522 words)

	Fil's FAQ-Link-In Corner: LinkIn: DTMF FAQ
		DTMF means: Dual Tone Multi-Frequency, There is no baseband multiplexing done on DTMF signals.
		The signal generated by a DTMF encoder is a direct algebraic summation, in real time, of the amplitudes of two sine (cosine) waves of different frequencies.
		These tones have not been used for general public service, and it would take years before these tones could be used in such things as customer information lines; such services would have to be compatible with the existing 12-button touch tone sets in any case.
	margo.student.utwente.nl /el/phone/dtmf.htm (2795 words)

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