Date   : Mon, 30 Apr 2007 23:37:51 +0100
From   : zeem.uk@... (Alex Taylor)
Subject: Tone Dialling Frequencies

On 30 Apr 2007, at 21:54, Ian Wolstenholme wrote:

> I'm sure this should be possible, but I can't get
> it to work - can the BBC sound chip generate
> the frequencies used for tone dialling on telephones?

I don't really know much about this, but out of interest I'm just  
looking at Wikipedia (http://en.wikipedia.org/wiki/DTMF) - there are  
7 different frequencies. Can the Beeb play these frequencies exactly?  
If so, are there any distortions present when playing the combination  
of tones together through the Beeb's hardware?

-- 
Alex Taylor