At 01:02 PM 8/06/98 +0200, you wrote: >> Van: talkworld >> Aan: PICLIST@MITVMA.MIT.EDU >> Onderwerp: Seeking Information >> Datum: vrijdag 5 juni 1998 11:21 >> >> Hi, >> >> I am sorry to put my troubles to you, but I saw a previous e-mail that >> did the same. >> >> I have been trying to obtain information on telephone dtmf translation, >> in particular ascii character which represent keys such as Recall >> button. >> >> I will be grateful if you can really help me with this. >> >> Regards >> Anthony > > >Hello Antony, > >DTMF is a way to send the numbers 0 thru 9, #, * and the special codes A >thru D by way of dual tones. One tone represents the Row and one the Line >(A 4-by-4 matrix). The intersection between these two represent the >pressed key. > >The Recall button does not generate any DTFM code, but is a direct signal >to the chip in your phone to (what else :-) redial the number it stored >from the last time. > >Try disconnecting the phone, reconnect, and pressing the 're-dial' button. >Most >likely you will hear nothing, because the phone lost it's memory :-) >because you took its power (the phone-line) away ... Incorrect! Most phones use EEPROM to store this information, even though it is not required (Phone lines are consisderd as always powered). You will find (If RAM is used) that the time for the phone to disscharge is quite long, as it may not draw more than 50uA on average from the line (Austel TS002, TS003) Also DTMF is used to send information over radio links, and a standard table of DTMF to ASCII also exits. Dennis > >Greetz, > Rudy Wieser > > -=====================================================================- Dennis Plunkett: Embedded Hardware, Software design NEC Australia DRMASS ph 03 9264-3867 -=====================================================================-