prindle@NADC.ARPA (Frank Prindle) (12/21/88)
I'm curious when the term DTMF (Dual Tone Multi Frequency) became synonymous with Touch Tone. As I recall, DTMF once designated the set of dual-tone frequencies used for in-band signaling on long distance trunks, which used a completely different set of tones than Touch Tone, and was always generated within the CO, not by any phone set (well, except for the "blue boxes"). I understand that this signaling technology has pretty much faded out, but didn't realize that TPC now uses the term DTMF to refer to Touch Tone (I can see how DTMF is a generic enough term to cover both, but thought they were historically quite different). Is my memory bad? Sincerely, Frank Prindle Prindle@NADC.arpa
jack@uunet.UU.NET (Jack Bonn) (12/22/88)
Frank Prindle (prindle@NADC.ARPA) writes: > I'm curious when the term DTMF (Dual Tone Multi Frequency) became synonymous > with Touch Tone. As I recall, DTMF once designated the set of dual-tone > frequencies used for in-band signaling on long distance trunks, which used > a completely different set of tones than Touch Tone, and was always generated > within the CO, not by any phone set (well, except for the "blue boxes"). The inter-office tone-based signaling system that was (is?) used in the US is referred to as MF signaling. It uses 2 out of 6 (2/6) tones to convey register signaling information between central offices. It also uses a 2600 Hz in-band supervisory signal on idle (the famous Cap'n Crunch tone) and was non-compelled and operated on a link-by-link (rather than an end-to-end) basis. Although MF's in-band supervisory signaling was vulnerable to fraud, its link-by-link, non-compelled nature gave it some definite speed advantages over R2 which was the prevalent trunk signaling system in most of the rest of the world at the same time. R2 uses end-to-end compelled signaling (where each tone is acknowledged) and is notoriously slow. I think that an international version of MF was called R1 in the CCITT <color> books. DTMF uses 7 or 8 frequencies, depending on the application, and is used primarily as a subscriber-line signaling system (although it also includes signaling between the CO and DID PABXs). Correct me if I'm wrong, but I don't think that DTMF was ever referred to as MF or the other way around. ---- Jack Bonn, <> Software Labs, Ltd, Box 451, Easton CT 06612 uunet!swlabs!jack (UUCP) jack%swlabs.uucp@uunet.uu.net (INTERNET)
ron@ron.rutgers.edu (Ron Natalie) (12/23/88)
> I'm curious when the term DTMF (Dual Tone Multi Frequency) became synonymous > with Touch Tone. It has been since day 1, most frequently used because TouchTone is a trademark. > As I recall, DTMF once designated the set of dual-tone > frequencies used for in-band signaling on long distance trunks, which used Those are referred to as simply "MF" tones.
grs@alobar.att.com (12/24/88)
>As I recall, DTMF once designated the set of dual-tone >frequencies used for in-band signaling on long distance trunks, which used >a completely different set of tones than Touch Tone, and was always generated >within the CO, not by any phone set (well, except for the "blue boxes"). Almost. What you're thinking of are MF, or Multi-Frequency tones. DTMF has always referred to "Touch Tone" tones. Definitely an honest mistake :-) Gregg Siegfried grs@alobar.att.com
hayes@ames.arc.nasa.gov (Jim Hayes) (12/25/88)
prindle@NADC.ARPA (Frank Prindle) writes in article <telecom-v08i0206m06@vector.UUCP>: >X-TELECOM-Digest: volume 8, issue 206, message 6 > >I'm curious when the term DTMF (Dual Tone Multi Frequency) became synonymous >with Touch Tone. As I recall, DTMF once designated the set of dual-tone >frequencies used for in-band signaling on long distance trunks, which used >a completely different set of tones than Touch Tone, and was always generated >within the CO, not by any phone set (well, except for the "blue boxes"). The in-band signaling is called MTMF. (Multiple Tone-Multiple Frequency), TouchTone has always been called DTMF. MTMF is on its way out, but is certainly not gone yet and I doubt it will fade completely anytime soon. There is some great reading in _The Bell System Technical Journal_ (which has had several name changes over the years.) I recently visited the New York Public Library (the biggy in the middle of the city) and got a complete tutorial on the evolution of ESS, cellular phones, signaling, call routing and TSPS. Free, written by the designers. Just find a empty microfilm machine and plan to spend about 8 hours reading. -Jim Hayes Advanced Micro Devices, Inc., Sunnyvale CA. hayes@amdcad.amd.com /earth: file system full {ucbvax|sun|decwrl}!amdcad!hayes These are not opinions of AMD.
imp@crayview.msi.umn.edu (Chuck Lukaszewski) (12/26/88)
In article <telecom-v08i0206m06@vector.UUCP>, prindle@NADC.ARPA (Frank Prindle) writes: > I'm curious when the term DTMF (Dual Tone Multi Frequency) became synonymous > with Touch Tone. As I recall, DTMF once designated the set of dual-tone > frequencies used for in-band signaling on long distance trunks, which used > a completely different set of tones than Touch Tone, and was always generated Actually, DTMF has always been generated by premises telephones. The in-band signalling to which you refer was done with single MF tones which were on 200-Khz frequency multiples. The DTMF tones, by contrast, are combinations of highly unique frequencies to minimize the potential of duplicating them though nature (or something like that - it's been a while). The whole blue box thing got started when the Bell System Technical Journal published a paper which happened to contain the actual MF signalling frequencies. ______________________________________________________________________________ Chuck Lukaszewski imp@crayview.msi.umn.edu 612 789 0931
dave@rutgers.edu (Dave Levenson) (12/26/88)
In article <telecom-v08i0208m01@vector.UUCP>, swlabs!jack@uunet.UU.NET (Jack Bonn) writes: (in reply to Frank Prindle's question regarding DTMF vs MF) ... > The inter-office tone-based signaling system that was (is?) used in the US > is referred to as MF signaling. It uses 2 out of 6 (2/6) tones to convey > register signaling information between central offices. It also uses a > 2600 Hz in-band supervisory signal ... Perhaps I'm nit-picking, but the MF singaling includes only the 2/6 tone set that conveys addressing information. The in-band 2600 Hz supervisory signaling (called SF) was often used on the same trunks that also used MF, but the two are not related. MF addressing is also used on trunks with E&M and other kinds of out-of-band supervisory signaling. SF supervision was also used on trunks where non-MF addressing was used. I can remember (the 1960's) when electromechanical switches sent dial-pulse signaling over inter-office trunks. If SF supervision was used on the trunks, the 2600 Hz supervisory signal was pulsed on and off to transmit the pulses. No MF was used. The "blue box" only enabled its user to commit toll-fraud on trunks where both SF and MF were used. There are very few such circuits still in use: As the toll networks become digital, supervision is taken care of with a low-speed digitally-multiplexed channel which occupies a single bit of the basic PCM timeslot. As common channel interoffice signalling (CCIS) is deployed, the address signalling moves to dedicated channels. -- Dave Levenson Westmark, Inc. The Man in the Mooney Warren, NJ USA {rutgers | att}!westmark!dave
dave@rutgers.edu (Dave Levenson) (12/26/88)
In article <telecom-v08i0208m02@vector.UUCP>, ron@ron.rutgers.edu (Ron Natalie) writes: > ... TouchTone is a trademark. Actually, Touch Tone _was_ a trademark. -- Dave Levenson Westmark, Inc. The Man in the Mooney Warren, NJ USA {rutgers | att}!westmark!dave
dave@rutgers.edu (Dave Levenson) (12/31/88)
In article <telecom-v08i0209m04@vector.UUCP>, imp@crayview.msi.umn.edu (Chuck Lukaszewski) writes: > Actually, DTMF has always been generated by premises telephones. The in-band > signalling to which you refer was done with single MF tones which were on > 200-Khz frequency multiples.... Actually, the inter-office signaling uses tone-pairs. Each digit (and a couple of "control characters") is represented as two of five tones. The individual frequencies are spaced at 200 Hz (not kHz) intervals. -- Dave Levenson Westmark, Inc. The Man in the Mooney Warren, NJ USA {rutgers | att}!westmark!dave