Yet although the tones you hear when someone else receives a phone call are varied, interesting and informative, the tones that you hear when someone else makes a phone call (let’s call them call tones) have been the same since mobile phones first appeared, back in 1985. And although it’s almost second nature for mobile phone owners to set up one ring tone for callers they like and a different one for callers they don’t like, whoever you call, whether it’s your girlfriend, your mum or the income tax office, your phone always plays the same call tones.
When you, or anyone else, dial a number on your mobile phone, provided it’s the sort of mobile phone that has keys, and sometimes even if it doesn’t, you hear a
DTMF tone every time you press a number key, or an ikon that looks like one.The DTMF tones are close to, but not exactly the same as, the musical notes
↑D (which plays when you press button 1), E (2), #F (3.) A fourth pitch, #G, is reserved for special signals which control equipment, route the call or set its priority. The other numbers use the same three notes, but they add a second note so that the software that receives the call can tell the difference between 1, 4 and 7, which all play ↑D.Mobile phones are unique, by which I mean that I can’t think of any other machine that does it, in that pressing different buttons evokes different tones. The microwave and the washing machine play the same note for every button. Even Start and Stop play the same note. It’s a miracle that the machines don’t confuse the two.
If we could somehow de-couple the musical note from the number on the button, storing the string of musical notes elsewhere and playing them one by one as you dialled telephone numbers, it would be possible to play an arbitrary series of musical notes. If you dialled, say,
0141 496 0787, the phone could send the correct DTMF tones, but play a completely unrelated musical note every time you dialled a digit. Every time you pressed a digit, the phone would play the next note of some piece of music, be it Beethoven’s Fifth Symphony or The Birdie SongBut there’s more. The tune doesn’t have to be the same for every number that you call. Most mobile phone users, most of the time, don’t dial numbers at all. They choose the person they want to call from a list: boss, curry house, doctor, landlord, massage parlour. The phone knows the phone number and transmits the DTMF tones to the nearest mast in the right order. At the same time, it could find the call tone that puts you in the right mood for talking to that person and play that music as it dialled the number. That would put you in the right mood for speaking to that person, and you wouldn’t have to listen to all those tuneless DTMF squawks.
Since it is widely believed that three pictures are worth three thousand words, here is an explanation in graphical form:
Out with the old | In with the new | What are all the other buttons for? |
Here are the DTMF tones 0141 496 0787 in
Wav format,
which works on most browsers, and in
Ogg format,
which works on Chrome.
,
Here too are the same DTMF tones, or at least the musical notes nearest to them,
woven into five seconds of music.
So you could dial 0141 496 0787 and the phone could play the first eleven notes of Twinkle, twinkle, little star, which would get it as far as ‘wonder’, but no farther because the phone number only has eleven digits.
If you don’t like listening to Twinkle, twinkle, little star, and I don’t blame you, you could make the phone play anything you wanted. For instance, while it dials your boss, you could make the phone play The Imperial March (that’s Darth Vader’s theme from Star Wars,) or Elvis Presley’s Big Boss Man?
Which means it is possible to make a mobile phone which plays
God save the King as you dial. It sounds just the right thing for brightening up those tiresome quiet coaches on long distance trains — but, sadly, those four DTMF tones will only get you through the first six notes of the National Anthem.