Nice job. I saw something like this a little while ago [1] which showed the Hayes AT-DT command but otherwise was pretty limited. Don't forget to use the Network tools to throttle your connection for a more faithful experience!

Feedback:

- The click sound is absurdly loud.

- Is 31,200 bps a UK thing? I grew up in the era of 14.4, 28.8, and 33.6 kbps.

- You should chop up the audio file so the number of tones matches the number of digits in the phone number field.

[1] - https://dialupmodemsound.com