Dan Lloyd wrote:

> Can anyone furnish me with a list of the frequencies which correspond to
> those used in 'tone' dialling; 0-9, #, * ?

  Someone else has provided the frequencies, presumably correctly.
To go just one better though, download:
        http://www.semicon.mitel.com/cgi-bin/doclist?bk1/dtmf/mt8870d
.. which gives the frequencies, as well as the data on a suitable
decoder
and other odds and ends.

  Cheers,
        Paul B.