[jeroenhd]

If you are the dialer app, you could generate DTMF tones, yes.

If you want to do dialer things without being the dialer, then no. Android doesn't permit apps to access the audio streams of a call to non-dialer apps.

In this case, the solution was to use an accessibility service to perform accessibility tasks as an accessibility app. Quite appropriate, I think. Although it will fail if the dialer of your choice doesn't have a keypad with the exact right labels (or numbers? I don't know if phones in writing systems with alternative numbers still show Arabic numerals on the dialer).

[EDM115]

indeed, non latin characters will probably fuck up my solution :(