tholome@portia.stanford.edu (Eric THOLOME) (01/07/91)
Can anyone tell me the frequencies used by pulse-mode phones when dialing? Thanks! Eric THOLOME tholome@isl.stanford.edu Stanford University [Moderator's Note: I was unaware that 'pulse', or rotary dial phones generated any frequencies or tones. PAT]
dave@westmark.westmark.com (Dave Levenson) (01/07/91)
In article <15841@accuvax.nwu.edu>, tholome@portia.stanford.edu (Eric THOLOME) writes: > Can anyone tell me the frequencies used by pulse-mode phones when > dialing? ... > [Moderator's Note: I was unaware that 'pulse', or rotary dial phones > generated any frequencies or tones. PAT] The last time I checked, pulse-dial phones generate a 'frequency' of approximately 10 Hz. (Ten dial-pulses per second.) Probably a bit low to be called a 'tone' but definitely a repetitive event, and that means that it has a frequency! Dave Levenson Internet: dave@westmark.com Westmark, Inc. UUCP: {uunet | rutgers | att}!westmark!dave Warren, NJ, USA AT&T Mail: !westmark!dave Voice: 908 647 0900 Fax: 908 647 6857
grayt@uunet.uu.net (Tom Gray) (01/08/91)
In article <15841@accuvax.nwu.edu> tholome@portia.stanford.edu (Eric THOLOME) writes: >Can anyone tell me the frequencies used by pulse-mode phones when >dialing? The pulse frequency is nominally 10pps (in North America). Most switches will accomodate frequencies from 7 to 12pps. The nominal make/break ration is 60/40. Most swtches will accomodate make breaks from 80/20 to 20/80. Outside of North America the nominal pulse rates vary from country to country but is most commonly 10pps with a 66/34 make/break.
meier@uunet.uu.net (Rolf Meier) (01/08/91)
In article <15841@accuvax.nwu.edu> tholome@portia.stanford.edu (Eric THOLOME) writes: >Can anyone tell me the frequencies used by pulse-mode phones when >dialing? Dial pulses can be anywhere from 8 to 12 pulses per second and still be recognized. Some fast operators are specified to work up to 20 pps. Who cares about dial pulsing any more anyway? Rolf Meier Mitel Corporation
seanwilliams@attmail.com (01/09/91)
Eric Tholome <tholome@portia.stanford.edu> writes: >> ...I am looking for the frequencies used in tone mode phones. I know each >> key generates two frequencies more or less based on C D and E music notes, >> but I would like something a little bit more precise. 1209 1336 1477 1633 <- Hertz ___ ___ ___ ___ | | | | | | | | | 1 | | 2 | | 3 | | A | 0697 When a key is pressed |___| |___| |___| |___| a single frequency ___ ___ ___ ___ from the low group | | | | | | | | and a single frequency | 4 | | 5 | | 6 | | B | 0770 from the high group |___| |___| |___| |___| are generated simul- ___ ___ ___ ___ taneously. Both | | | | | | | | frequencies must exist | 7 | | 8 | | 9 | | C | 0852 for the carrier equip- |___| |___| |___| |___| ment to recognize the ___ ___ ___ ___ signal. | | | | | | | | | * | | 0 | | # | | D | 0941 |___| |___| |___| |___| The frequency pairs shown above are used throughout the world where tone signalling is utilized. The tones have been carefully selected so that the processing circuits in the central office will not confuse them with other tones which may occur on the line. The time required for the central office to recognize any digit tone is 50 milliseconds with an interdigit interval of another 50 milliseconds. The term "Touch-Tone(tm)" is a trademark of AT&T. Sources: "Understanding Telephone Electronics" Texas Instruments Inc., 1983. "Data Communications: A User's Guide" Ken Sherman, Simon & Schuster, 1990. Sean E. Williams seanwilliams@attmail.com
jon_sree@world.std.com (Jon Sreekanth) (01/10/91)
In article <15852@accuvax.nwu.edu> mitel!Software!meier@uunet.uu.net (Rolf Meier) writes: Some fast operators are specified to work up to 20 pps. I have a Uniden phone that I bought around 1986, and it has a three position switch : DTMF, 10pps pulse, 20pps pulse. I've not had any problems using 20pps in CA and MA (but in well populated suburban areas). Who cares about dial pulsing any more anyway? I understand it's still widely used outside North America. On this topic, why do many voice mail and other phone operated services insist on users having DTMF phones ? Is it really hard to detect pulse mode digits? I can see that the low numbers might be a problem, (can't distinguish it from a noise pulse), but if one saw five to ten regularly spaced pulses, isn't that adequate for recognition? I've seen AT&T answering machines which say on the box that they work with pulse phones (at the remote end, for checking one's messages). I haven't played with them. Does anyone know how they work, or how reliable the detection is ? Regards, Jon Sreekanth Assabet Valley Microsystems Fax and PC products 346 Lincoln St #722, Marlboro, MA 01752 508-562-0722 jon_sree@world.std.com [Moderator's Note: The old Unitel (United Airlines) internal phone network was able to recognize pulse dialing on the in-dial to their call-extender here several years ago. Don't ask me how they did it. I did note at the time that tone signals were more reliable. PAT]
Jim.Redelfs@iugate.unomaha.edu (Jim Redelfs) (01/12/91)
> Can anyone tell me the frequencies used by pulse-mode phones when > dialing? > [Moderator's Note: I was unaware that 'pulse', or rotary dial phones > generated any frequencies or tones. PAT] They DON'T! They simply flash/open-close/pulse the loop - the appropriate number of times for each digit. I've successfully "dialed" a call using only the switchook. (It is a challenge!) JR Copernicus V1.02 Elkhorn, NE [200:5010/666.14] (200:5010/2.14)
julian%bongo.UUCP@nosc.mil (Julian Macassey) (01/13/91)
In article <15962@accuvax.nwu.edu> jon_sree@world.std.com (Jon Sreekanth) writes: X-Telecom-Digest: Volume 11, Issue 23, Message 6 of 6 >On this topic, why do many voice mail and other phone operated >services insist on users having DTMF phones ? Is it really hard to >detect pulse mode digits? I can see that the low numbers might be a >problem, (can't distinguish it from a noise pulse), but if one saw >five to ten regularly spaced pulses, isn't that adequate for >recognition? The reason is that the pulse is a DC disconnection at your phone instrument. This disconnection and therefore interruption of the DC current extends only to your local CO. The far end will just hear a click. Hearing the click above line noise is tricky. So yes, at the far end, these are not "pulses" of 0 - 10V with 300V transients, but clicks, not quite the same thing. DTMF on the other hand is still DTMF after it has been down a fiber optic cable and across two satellite links. Touch Tone was invented so subscriber signalling could be carried over radio (microwave etc) circuits. Pulse dialling will not work unless you have copper wire carrying DC - yes, subscriber carrier excepted. Voice mail boxes, etc work well with DTMF and miserably trying to listen for clicks. Then DTMF is also faster than pulse. Plus of course there is no pulse equivalent for * and # (-: In the UK, a bank was offering a dial in interactive account service. Because of the dearth of DTMF phones in the UK, part of the banks deal was a ten pound (money) deposit for a hand held DTMF generator that you held to the mouthpiece to punch in your account number etc. >I've seen AT&T answering machines which say on the box that they >work with pulse phones (at the remote end, for checking one's >messages). I haven't played with them. Does anyone know how they >work, or how reliable the detection is? Not too reliable I would guess. DTMF = Dual Tone Multi Frquency = Touch Tone CO = Cental Office = Telephone Exchange Julian Macassey, n6are julian@bongo.info.com ucla-an!denwa!bongo!julian N6ARE@N6YN (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495